Would you mind sharing the screenshot of the error message for a better understanding? Also, please log out of the application, reboot the computer once, and re-loging with the same Adobe ID and check if that helps.
Same problem: virtually every time I open my newly purchased and paid for and licensed and installed Acrobat Pro 2020, it gives me this message (screenshot). So far, if I just hit RETURN it takes me on to the app properly, but it's annoying and I know that it can go bad and stop recognizing my right to use the software. I only bought this product because the Creative Cloud instance that my employer licenses was *never* reliable and kept forgetting that I was licensed even when CC showed Acrobat as installed. Is Acrobat just badly written software? Is there any way to use it as you would normal software?