We got it figured out. It was later on in the coding. It was a matter of changing the line
user = admin.content.users.user(username=item.owner) to
user = admin.content.users.user(username=username).
It does lead me to another question, though. The purpose of our python code is to back up the feature layers that others are creating and updating on AGOL. Right now, the python code looks for a specific ItemID....is there a way to have the code go into a Members content and list all of their feature layers and itemIDs? This would be ideal since we may not be notified every time someone creates a new layer. Does that make sense? I haven't found a script that does it that way.