Thumb drive

Try using a different USB stick especially a different brand. The quality of USB sticks is extremely poor (even name brand ones).

Also make sure the both computers have an app that can actually work on that particular version of the file. If a file is created or edited on a newer version of an app, then sometimes an older version of the app will not understand the new file format used by the newer version of an app.

You can also use file sharing to exchange files between two computers.

https://support.apple.com/guide/mac-help/set-up-file-sharing-on-mac-mh17131/mac

what file are we trying to open or read?

does the usb show up on the macbook?

sometimes a weak power outlet could slow the macbook down like i experienced last year.

there a lot of solutions and "how to" like air drop and emailing files from the MacBook to imac

we just need more specifics like the size and other things