I am trying to concatenate all the email addresses associated with a company on one line.
I tried TEXTJOIN.
I am also open to VBA solutions.
Here is one way of doing this using MAP()
=MAP(A2:A19,LAMBDA(α,IF(ROW(α)=XMATCH(α,A:A),TEXTJOIN("; ",,FILTER(D:D,A:A=α)),"")))
The above formula will spill down, however if you want to drag down a formula then:
=TEXTJOIN("; ",,FILTER($D$2:$D$19,(A2=$A$2:$A$19)*(COUNTIF(A$2:A2,A2)=1),""))