Please go to the game settings and link your account to Google (to prevent progress loss).
After that go to device settings, find our game and select "Clear cache" and "Clear data". Then find Google Play and update it if any updates for it are available.
Get back to Google Play in device settings and clear its cache and data as well. Reboot your device afterwards and check if there are any changes.
Also please check Google Play Account Settings: make sure you have an active credit card or other payment method added to your Google Play account.
Check if the Google Play account is blocked for any reason.
If you are using a VPN, proxy server or parental control, try disabling it.