Everytime I want to open a PDF file a pop up comes up wanting me to log back into adobe

Hey there,

In your description I believe you are talking about Acrobat DC's subscription. Just to make sure, please check whether you are opening Acrobat DC or freeware Reader DC? 

1- There's a possibility you have been trying to open your PDFs through Acrobat Reader DC rather than Acrobat DC, as they both look identical. Resulting, login information.

So, please Open App>Help>About Acrobat what's the version you see?

2- Is it Acrobat DC? If yes, then Sign In Out of the app once. Open Acrobat>Help>Sign Out and Sign back In. 

Close Acrobat DC and reopen.

Still no luck? 

3- Follow the resolution provided here: https://helpx.adobe.com/in/download-install/kb/adobe-sign-in-loop.html

For better understanding, Help us with the screenshot when it asks password.

Thanks,

Akanchha