How to select and join field with max date?

The problem is you are selecting max(l.CREATEDDATETIME) in your select query but you are not doing anything to select the max date in your where clause. You have to put a where clause to select the row with max date out of your 3 rows. I have tried to modify your query, you might need to modify the table and column name but you will get the context once you go through it -

SELECT

    t.[Pro Number],
    t.CREATEDDATETIME,
    t.[Bill Date],
    t.RECID,
    l.AAALTLCHANGEVALUE,
    l.CREATEDDATETIME as Status_Date


FROM [AX2cTestStage].[dbo].[AAATRANSPORTTABLE_V] t
LEFT JOIN AX2cTestAdapter_dbo_AAALTLCHANGEREQUEST_V l 
ON t.RECID = l.AAATRANSPORTORDERRECID

WHERE t.[Pro Number] = '14521857'
AND l.CREATEDDATETIME = (select max(V.CREATEDDATETIME) from AX2cTestAdapter_dbo_AAALTLCHANGEREQUEST_V V where V.AAAREFNUMVALUE = '14521857')

GROUP by l.CREATEDDATETIME,t.[Pro Number],t.CREATEDDATETIME,t.[Bill Date],t.RECID,l.AAALTLCHANGEVALUE

It is impossible to get that desired result from your data because that given date in desired data even doesn't exist in any of the tables. However, from your definition this should be what you are after:

SELECT

    t.[ProNumber],
    t.CREATEDDATETIME,
    t.[BillDate],
    t.RECID,
    l.AAALTLCHANGEVALUE,
    l.CREATEDDATETIME as Status_Date


FROM [AAATRANSPORTTABLE] t
LEFT JOIN (
    select t1.AAATRANSPORTORDERRECID, t1.AAALTLCHANGEVALUE, t1.CREATEDDATETIME 
    from AAALTLCHANGEREQUEST t1
    inner join (
          select AAATRANSPORTORDERRECID, max(CREATEDDATETIME) as maxDate 
          from AAALTLCHANGEREQUEST
          group by AAATRANSPORTORDERRECID) t2 
          on t1.AAATRANSPORTORDERRECID = t2.AAATRANSPORTORDERRECID 
             and t1.CREATEDDATETIME = t2.MaxDate) l
    ON t.RECID = l.AAATRANSPORTORDERRECID
WHERE t.[ProNumber] = '14521857';

DBFiddle Demo

PS: You don't need any group by on the main select, it is needed only for getting the max date per group.