Unmatched wrap character for a wrapped field with comma in it

First of you need to check what your lines end with, you've defined it as LF, but if it is CR LF it will throw the error above. Change it to 0x0D 0x0A on the root node.

If you then get the below, then the final line doesn't have the delimiter and you need to change the child order on the root node LMS Certificate to Infix.

The current definition being parsed is Certificate. The stream offset where the error occured is 227. The line number where the error occured is 3. The column where the error occured is 72.

Next you will get the below errors

The 'DateCompleted' element is invalid - The value '1/12/2021' is invalid according to its datatype 'http://www.w3.org/2001/XMLSchema:date' - The string '1/12/2021' is not a valid Date value.
The 'DateDue' element is invalid - The value '15/12/2022, 07:55' is invalid according to its datatype 'DateTime' - The string '15/12/2022, 07:55' is not a valid DateTime value.
The 'DateCompleted' element is invalid - The value '1/12/2021' is invalid according to its datatype 'http://www.w3.org/2001/XMLSchema:date' - The string '1/12/2021' is not a valid Date value.
The 'DateDue' element is invalid - The value '30/11/2023, 09:10' is invalid according to its datatype 'DateTime' - The string '30/11/2023, 09:10' is not a valid DateTime value.

Set the DateCompleted Custom Date/Time Format to d/MM/yyyy, that will eliminate two of the errors.

Now the DueDate one is tricky, I tried a Custom Date/Time Format of d/MM/yyyy, hh:mm, but it didn't work and stil threw the same two errors. If I changed it to a String it parsed correctly. A clue was when I generated an native instance was that it would populate it as DueDate. After I copied your other date and renamed it, updated it to a DateTime and updated the custom format it worked.

Differences

• child_delimiter="0x0D 0x0A" on LMSCertificate
• Not sure if this got corrupted when you posted to StackOveflow, but wrap_char=""" isn't valid, it should be wrap_char="""
• datetime_format="d/MM/yyyy" on DateCompleted
• pad_char_type="hex" pad_char="0x20" datetime_format="d/MM/yyyy, hh:mm" on DueDate

<?xml version="1.0" encoding="utf-16"?>
<xs:schema xmlns="http://Securitas.ESB.HR.LMSToAfas_ManageCertificate.Schemas.LMSCertificate" xmlns:b="http://schemas.microsoft.com/BizTalk/2003" targetNamespace="http://Securitas.ESB.HR.LMSToAfas_ManageCertificate.Schemas.LMSCertificate" xmlns:xs="http://www.w3.org/2001/XMLSchema">
  <xs:annotation>
    <xs:appinfo>
      <schemaEditorExtension:schemaInfo namespaceAlias="b" extensionClass="Microsoft.BizTalk.FlatFileExtension.FlatFileExtension" standardName="Flat File" xmlns:schemaEditorExtension="http://schemas.microsoft.com/BizTalk/2003/SchemaEditorExtensions" />
      <b:schemaInfo standard="Flat File" codepage="65001" pad_char_type="char" count_positions_by_byte="false" parser_optimization="speed" lookahead_depth="3" suppress_empty_nodes="false" generate_empty_nodes="true" allow_early_termination="false" early_terminate_optional_fields="false" allow_message_breakup_of_infix_root="false" compile_parse_tables="false" root_reference="LMSCertificate" />
    </xs:appinfo>
  </xs:annotation>
  <xs:element name="LMSCertificate">
    <xs:annotation>
      <xs:appinfo>
        <b:recordInfo structure="delimited" child_delimiter_type="hex" child_delimiter="0x0D 0x0A" child_order="postfix" sequence_number="1" preserve_delimiter_for_empty_data="true" suppress_trailing_delimiters="false" />
      </xs:appinfo>
    </xs:annotation>
    <xs:complexType>
      <xs:sequence>
        <xs:annotation>
          <xs:appinfo>
            <groupInfo sequence_number="0" xmlns="http://schemas.microsoft.com/BizTalk/2003" />
          </xs:appinfo>
        </xs:annotation>
        <xs:element name="Header">
          <xs:annotation>
            <xs:appinfo>
              <b:recordInfo structure="delimited" child_delimiter_type="char" child_delimiter="," child_order="infix" sequence_number="1" preserve_delimiter_for_empty_data="true" suppress_trailing_delimiters="false" />
            </xs:appinfo>
          </xs:annotation>
          <xs:complexType>
            <xs:sequence>
              <xs:annotation>
                <xs:appinfo>
                  <groupInfo sequence_number="0" xmlns="http://schemas.microsoft.com/BizTalk/2003" />
                </xs:appinfo>
              </xs:annotation>
              <xs:element name="Username" type="xs:string">
                <xs:annotation>
                  <xs:appinfo>
                    <b:fieldInfo justification="left" sequence_number="1" />
                  </xs:appinfo>
                </xs:annotation>
              </xs:element>
              <xs:element name="CertificationID" type="xs:string">
                <xs:annotation>
                  <xs:appinfo>
                    <b:fieldInfo justification="left" sequence_number="2" />
                  </xs:appinfo>
                </xs:annotation>
              </xs:element>
              <xs:element name="CertificationName" type="xs:string">
                <xs:annotation>
                  <xs:appinfo>
                    <b:fieldInfo justification="left" sequence_number="3" />
                  </xs:appinfo>
                </xs:annotation>
              </xs:element>
              <xs:element name="DateCompleted" type="xs:string">
                <xs:annotation>
                  <xs:appinfo>
                    <b:fieldInfo justification="left" sequence_number="4" />
                  </xs:appinfo>
                </xs:annotation>
              </xs:element>
              <xs:element name="DateDue" type="xs:string">
                <xs:annotation>
                  <xs:appinfo>
                    <b:fieldInfo justification="left" sequence_number="5" />
                  </xs:appinfo>
                </xs:annotation>
              </xs:element>
            </xs:sequence>
          </xs:complexType>
        </xs:element>
        <xs:element maxOccurs="unbounded" name="Certificate">
          <xs:annotation>
            <xs:appinfo>
              <b:recordInfo structure="delimited" child_delimiter_type="char" child_delimiter="," child_order="infix" sequence_number="2" preserve_delimiter_for_empty_data="true" suppress_trailing_delimiters="false" />
            </xs:appinfo>
          </xs:annotation>
          <xs:complexType>
            <xs:sequence>
              <xs:annotation>
                <xs:appinfo>
                  <groupInfo sequence_number="0" xmlns="http://schemas.microsoft.com/BizTalk/2003" />
                </xs:appinfo>
              </xs:annotation>
              <xs:element name="Username" type="xs:string">
                <xs:annotation>
                  <xs:appinfo>
                    <b:fieldInfo justification="left" sequence_number="1" />
                  </xs:appinfo>
                </xs:annotation>
              </xs:element>
              <xs:element name="CertificationID" type="xs:string">
                <xs:annotation>
                  <xs:appinfo>
                    <b:fieldInfo justification="left" sequence_number="2" />
                  </xs:appinfo>
                </xs:annotation>
              </xs:element>
              <xs:element name="CertificationName" type="xs:string">
                <xs:annotation>
                  <xs:appinfo>
                    <b:fieldInfo justification="left" sequence_number="3" wrap_char_type="char" pad_char_type="hex" pad_char="0x20" wrap_char="&quot;" />
                  </xs:appinfo>
                </xs:annotation>
              </xs:element>
              <xs:element name="DateCompleted" type="xs:date">
                <xs:annotation>
                  <xs:appinfo>
                    <b:fieldInfo justification="left" sequence_number="4" pad_char_type="hex" pad_char="0x20" datetime_format="d/MM/yyyy" />
                  </xs:appinfo>
                </xs:annotation>
              </xs:element>
              <xs:element name="DateDue" type="xs:dateTime">
                <xs:annotation>
                  <xs:appinfo>
                    <b:fieldInfo justification="left" pad_char_type="hex" pad_char="0x20" datetime_format="d/MM/yyyy, hh:mm" sequence_number="5" wrap_char_type="char" wrap_char="&quot;" />
                  </xs:appinfo>
                </xs:annotation>
              </xs:element>
            </xs:sequence>
          </xs:complexType>
        </xs:element>
      </xs:sequence>
    </xs:complexType>
  </xs:element>
</xs:schema>

Output

<LMSCertificate xmlns="http://Securitas.ESB.HR.LMSToAfas_ManageCertificate.Schemas.LMSCertificate">
    <Header xmlns="">
        <Username>Username</Username>
        <CertificationID>"Certification ID number"</CertificationID>
        <CertificationName>"Certification Name"</CertificationName>
        <DateCompleted>"Date completed"</DateCompleted>
        <DateDue>"Date due"</DateDue>
    </Header>
    <Certificate xmlns="">
        <Username>nlxxxxxx</Username>
        <CertificationID>NLaaa</CertificationID>
        <CertificationName>NL - Test certificaat</CertificationName>
        <DateCompleted>2021-12-01</DateCompleted>
        <DateDue>2022-12-15T07:55:00.0000000</DateDue>
    </Certificate>
    <Certificate xmlns="">
        <Username>nlyyyyyy</Username>
        <CertificationID>CPbbb-cert</CertificationID>
        <CertificationName>Test Law certificaat</CertificationName>
        <DateCompleted>2021-12-01</DateCompleted>
        <DateDue>2023-11-30T09:10:00.0000000</DateDue>
    </Certificate>
</LMSCertificate>

P.S. I also assumed that the extra lines in your sample were due to trying to format it for StackOverflow, and that it actually looks like this

Username,"Certification ID number","Certification Name","Date completed","Date due"
nlxxxxxx,NLaaa,"NL - Test certificaat",1/12/2021,"15/12/2022, 07:55"
nlyyyyyy,CPbbb-cert,"Test Law certificaat",1/12/2021,"30/11/2023, 09:10"