It is a new Tablet I just bought it last month. I also have AVG Anti virus programme on it.
Could you share a screenshot of the second issue. The first could be because the tablet isn't supported.
Give these a try:
- Make sure your Google Play Store app is up to date.
- In Settings -> Display -> Screen Resolution, make sure you are running at FHD+ or WQHD+ resolution (not HD+ resolution).
- In Settings -> Apps -> Google Play Store -> Storage, tap Clear Data & Clear Cache. Only clearing the cache is not enough so make sure you clean the data too.
- Reboot your device.
- Make sure you accepted the Terms of Service of Google Play.
