Your system doesn't support contacts.
You need to install or enable PDO (SQLite / MySQL / PostgreSQL) exstenstion on your server.

Contacts

Enable contacts

Type

PDO (MySQL / PostgreSQL / ...)

Dsn

Examples:
mysql:host=127.0.0.1;port=3306;dbname=rainloop
pgsql:host=127.0.0.1;port=5432;dbname=rainloop

User

Password

PDO (SQLite)

Don't use this type of database with a large number of active users.