I think the reason your post hasn't received a response is that you already appear to have the answer:
"Microsoft Drivers for SQL Server for PHP are not installed or not configured properly."
You'll need to investigate and solve this problem. If your other sites use MYSQL, but your Moodle uses MSSQL, well it's a fair bet that your problem is with the MSSQL setup. Contact your hosting provider and/or view their documentation about this.
If it all looks good, but the problem persists, please post again here with as much information as you can provide.
For now though, it looks like your problem is, "Microsoft Drivers for SQL Server for PHP are not installed or not configured properly."
"Microsoft Drivers for SQL Server for PHP are not installed or not configured properly."
You'll need to investigate and solve this problem. If your other sites use MYSQL, but your Moodle uses MSSQL, well it's a fair bet that your problem is with the MSSQL setup. Contact your hosting provider and/or view their documentation about this.
If it all looks good, but the problem persists, please post again here with as much information as you can provide.
For now though, it looks like your problem is, "Microsoft Drivers for SQL Server for PHP are not installed or not configured properly."