Zorin 15.3 doesn't boot with a separate data storage HDD

[citfta]

Here is one of the results I got when I did a search on this forum. There are several others you can try if this doesn't work.

Can't copy/move files to external drive Z16 pro

Okay, so the noob in me is in full force today. I'm trying to copy some files onto my external drive, but it won't allow me. Yes, I've checked the permissions which say I have full write privileges, but I can't create a new folder in it, and I also can't copy a folder to it. In terminal I get this error: cp: -r not specified I can't find the answer on google. Can someone here explain, please?