Installation: Access denied for user oc_admin

I’m trying to install NC13, but at the setup page when I insert administrator new credential, data and database info, I get the error:

Error while trying to create admin user: Failed to connect to the database: An exception occured in driver: SQLSTATE[HY000] [1044] Access denied for user 'oc_admin'@'localhost' to database 'nextcloud' 

I can see that the db user oc_admin is created.
Where could the problem be?

I’ve solved this issue with the suggestion posted here