User registration on two sites in same multisite

You could use a plugin such as
Join My Multisite – https://wordpress.org/plugins/join-my-multisite/

The plugin allows you to set if a user is a member of site1 and visits site2, automatically add site2 to the user’s sites. So you avoid them making another account.

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)