I applied to U of M and I already sent in my common app and my high school/community college transcripts When I first took the ACT they allowed me to choose 4 universities to send it to. I chose U of M as one of the 4, but this was in 2015. I went on the ACT website to confirm that it was sent to Umich in 2015. I even called Umich and they said they have it. But do I need to resend it? Thanks.
UMich says they have it. So unless they let you know that something is missing from your application file, I think you are fine.