Steps for troubleshooting Google Play Store Errors
Problem : I couldn't download apps from playstore
Step 1:
Go to settings >Apps>Google Play Store
Clear cache, clear data and force stop.
Similarly clear cache memory for Google play services, download manager and Downloader.
Note : After clearing cache and data you will have to login into your Google account.

Step 2:
Go to settings >other account
Remove all Google accounts, restart your phone.
Create a new Google account and log in.
You can log into your Google id afterwards and set it as default.

Step 3:
Uninstall GMS and all Google apps and services including play services.
Go to security (flyme) app and run cleaner.
Restart your phone.
Install GMS from hot apps or from App store.
Note : Uninstalling Google services may affect the functionality of your phone so proceed with caution.

Step 4:
If none of the above steps works try flashing your firmware or update your phone to the latest version.