Hey Jai - are you using an actual MSSQL instance other than default? If so, reference this article: https://community.lansweeper.com/t5/installation/configuring-a-sql-server-instance-to-host-the-lansw...
If not, try just using the SQL server name. Here's me attempting an install on my existing installation (which is why it's complaining as it makes the lansweeperdb database which is already there):
