You're in a group library that doesn't allow file editing.
Where are you trying this? In the desktop app or the web library? It's possible the error message for this in the web library is still somewhat unclear.
I also cannot upload PDFs to collections located in a group library, which I have access to. I am using the desktop version and can easily add PDF to my local library, but when ever I try to add to one of the group folder it either does not allow the upload or links to the web address
That's about data, not files. You're in two group libraries, and one doesn't allow file access. You'll need to speak to the group admin. (But it should also be clear, because there wouldn't be any stored files in the group.)
Cannot upload a pdf file in a library, which i have admin access, but can in my own.
You're in a group library that doesn't allow file editing.
Where are you trying this? In the desktop app or the web library? It's possible the error message for this in the web library is still somewhat unclear.