Hope you are doing well and sorry for the trouble. As described you are unable to create PDF via Word plugin in Mac and getting the above error message.
I have checked the Adobe account with the email you are using on this community and found that you have the personal as well as the school profile linked with the same Adobe ID/email. Make sure you are using the school profile to login to the Adobe Acrobat.
Please try to create the PDF from the file menu of Adobe Acrobat and see if that works. Open the Acrobat DC application > File > Create > PDF from file and select the Word file you want to convert to PDF.