Recall from my previous post Configuring SQL Server Authentication in Microsoft Dynamics NAV 2016 – Part-1, action is almost similar with few small differences when dealing with Multitenant Deployment.
Configure SQL Server Authentication on Microsoft NAV Server Instance in a Multitenant Deployment
How to configure a Microsoft Dynamics NAV database to use SQL Server Authentication with a Microsoft Dynamics NAV Server instance.
To configure a SQL Server Authentication on a Microsoft Dynamics NAV Server instance, you set up the server instance with the login credentials (user name and password) for the user accounts for the application and tenant databases in SQL Server.
Encryption keys are used to help secure the login credentials over the connection between the Microsoft Dynamics NAV Server instance and the Microsoft Dynamics NAV database in SQL Server.
This dialog box is to inform you to enable encryption on SQL Server connections, which is disabled by default.
If the tenant is already mounted to the Microsoft Dynamics NAV Server instance, you must dismount the tenant, and mount it again.
Restart the server instance.