Hope you are doing well and sorry for the trouble. As described you are not able to create PDF from scan.
Is this a behavior with a particular document or with all the documents you try to scan? Please try to scan a different PDF file and check.
Would you mind sharing the version of the Adobe Acrobat DC you are using? To check the version go to Help > About Acrobat and make sure you have the latest version 20.13.20074 installed. Go to Help > Check for updates.
What is the make and model of the scanner you are using? Please check for any missing/pending update for scanner driver and firmware and try updating them and reboot the computer once and see if that helps.