Hope you are doing well and sorry for the trouble. As described you are unable to open the PDF file and needed to force quit Acrobat Pro DC several times.
- Is this a behavior with a particular PDF file or with all the PDFs? Please try with a different PDF file and check.
- Is the file located on a shared network/drive? If yes, please try to download it to your computer first and then try to open it with Adobe Acrobat DC and see if that helps.
- What is the version of the Adobe Acrobat DC you are using? To check the version of the application go to Help > About Acrobat and make sure you have the latest version 21.01.20142 installed. Go to Help > Check for Updates and reboot the computer once. Also, please check for any missing/pending updates for Mac OS and try updating it and check.