How to parse data from individual records instead of the complete file

I am creating a program that uses a title and author to get data. Until now, I was able to get all the data using BeautifulSoup and it's lxml parser, but I seem to have hit a wall, and I don't know how to overcome it.

The Situation: I am processing this data: https://sru.k10plus.de/opac-de-627!rec=1?version=1.1&operation=searchRetrieve&query=pica.tit%3DGeschichten%20aus%20unserer%20Zeit+and+pica.all%3DHotz,%20Karl&maximumRecords=100&recordSchema=marcxml

and am trying to get data from the fields 245, 250, 583 and 924. They can appear multiple times in the response, and contain different data. Using Beautifulsoup works fine, but the problem is that I want to seperate the results based on the records, as some titles have the 583 entry and others do not, and I need to know which one has, based on 245, 583 and 924. But I have no Idea how to do this with BeautifulSoup

This is how the collapsed file looks like:

<zs:searchRetrieveResponse>
<zs:version>1.1</zs:version>
<zs:numberOfRecords>14</zs:numberOfRecords>
<zs:records>
<zs:record>    </zs:record>
<zs:record>    </zs:record>
<zs:record>    </zs:record>
<zs:record>    </zs:record>
<zs:record>    </zs:record>
<zs:record>    </zs:record>
<zs:record>    </zs:record>
<zs:record>    </zs:record>
<zs:record>    </zs:record>
<zs:record>    </zs:record>
<zs:record>    </zs:record>
<zs:record>    </zs:record>
<zs:record>    </zs:record>
<zs:record>    </zs:record>
</zs:records>
<zs:echoedSearchRetrieveRequest>
<zs:version>1.1</zs:version>
<zs:query>
pica.tit=Geschichten aus unserer Zeit and pica.all=Hotz, Karl
</zs:query>
<zs:maximumRecords>100</zs:maximumRecords>
<zs:recordPacking>xml</zs:recordPacking>
<zs:recordSchema>marcxml</zs:recordSchema>
</zs:echoedSearchRetrieveRequest>
</zs:searchRetrieveResponse>

and I want to iterate over every <zs:record> and check the contents. This is how I currently search the whole response:

    r = requests.get(all_url)
    r.encoding = 'utf-8'
    if r.status_code == 200:
        #count=search_url_xml(all_url)
        count=0
        is_list=[]
        issues=[]
        de640l=[]
        soup = BeautifulSoup(r.text, 'lxml')
        for datafield in soup.find_all("datafield"):
            
            #try:
                
                if datafield['tag'] == '250': #get all issues
                    subfield_a = datafield.find_next("subfield",{"code":"a"})
                    if subfield_a != None:
                        issue=subfield_a.text
                        if issue not in issues:
                            issues.append(issue)
                    #find all datafields with the tag 924 before the next datafield with the tag 250
                    datafield_924 = datafield.find_all("datafield",{"tag":"924"})
                    
                if datafield['tag'] == "583":
                    subfield_z = datafield.find_next("subfield",{"code":"z"})
                    de640=subfield_z.text
                    #if de640 not in de640l:
                    de640l.append(de640)
             
        for issue in issues:
            issuelist={'issue':[],'amount':[],'de640':[]}   
            issuelist['issue'].append(issue)
            issuelist['amount'].append(issues.count(issue))
            issuelist['de640'].append(de640l[0])
            is_list.append(issuelist)

I have thought about changing over to some XML API like etree, but I don't really have much experience with that.

How would I do that?