Where are my Photos? Photo library not found after latest update.

I bought a new MacBook Pro 16" a couple of weeks ago. I used migration assistant to transfer everything to my new MBP from my old MBP (2017-15"). Everything worked smoothly. But today I tried to access my photos from "Photos" and it said: Photos cannot find the System Photo Library named “Photos Library.photoslibrary” It suggests opening another library to attach to Photos Library but I don't know what I'm doing in that area and don't want to do something wrong.

Can someone help me figure out how to get my iCloud photos to display in Photos on the Mac? (My iPad and iPhone both show my pictures so I know they are still in iCloud.)

Thank you!