In my case, I had two google accounts synced so I had one that was a pay account and the "other" was not. The "other" was the primary account so it would give the error.
Solution: I removed the secondary google account which made my pay account the primary account. This solved my problem.
This worked for me too! Pay account wasn't the primary account on my tablet. Once I deleted the primary account on the tablet, the error message stopped and I can download again! I was even able to add back I'm my other account as the secondary account. Thank you!
I was able to get it fixed by clearing the data for Google Play Store, Google Play Services, Google Services Framework & Google Account Manager. Once I did that I forced closed all of the aforementioned apps and I was able to download from the Play Store. The only thing was it didn't recognize any of the apps that I had purchased. I removed my Google account from the device, re-added it, rebooted and everything was fine. Good luck to you!