Follow the steps below to Install and Configure SQL Server on Secondary Server.
1. Install SQL Server on Secondary Machine.
2. Install the Client Setup of SQL Server on the primary machine.
3. Configure SQL Server in HC settings as explained here https://www.hostingcontroller.com/english/help/host/help/default.htm#configuring_sql_server_with_hc.htm.
If SQL Server is on remote machine, then you need to run SQL Server Client Setup on the primary machine where HC is running. You will see the Client Setup option when you run the SQL setup. SQL client setup mainly installs few components called SQL DMO, which are needed in order to programmatically perform SQL server operations. SQL server enterprise manager also uses same components.