An instance is a logical entity that you use to manage backup and restore operations for all the databases that are created in that instance.
By default, the software automatically discovers and displays the instances that are available on the SQL Server .
From the navigation pane, go to Protect > Databases.
The Instances page appears.
Click Add Instance, and then select SQL server.
The Add SQL server instance dialog box appears.
From the Server name list, select the server that contains the SQL instance that you want to add.
From the SQL Server instance list, select the SQL instance.
From the Plan list, select the server plan that you want to use for the SQL instance.
To use a user account for backup and restore operations, under SQL server authentication, move the Override higher levels settings toggle key to the right, and then do one of the following:
Use Local System Account - To use the local system account, select this option.
Impersonate user: To use a SQL server user account, select this option, and from the Credentials list, select the credential for the SQL server user account.
Verify that the account that you want to use can perform backup and restore operations.
Tip: To create a new credential, beside the Credentials list, click Create new.