I found the solution and it has worked perfectly! Only hayq ue go to Settings> Backup> Factory Data Reset
It is a widespread problem and have found the solution in the web of BQ:
We encountered a problem with the connection to Google Play Store in the Aquaris 4 thanks to the comments that you have made to us by users. This occurs in some specific cases where the device ID is not generated correctly, and so Google Play Store does not allow us to connect to their servers.
The solution is to reset the phone to factory data, and thus force it to generate a new device ID.
To do this, you must go to Settings> Backup> Factory Data Reset.
This procedure should resolve this problem. If not, contact Support and from there will tell you how to proceed.