It seems that the driver is configured to connect to SQL Server using SSL, you will have to disable that or ask which server name and port you need to use in the driver.
On a separate note, I would not use Qlik's connectors especfically for SQL Server since they are built in the Windows operating system, more updated and if anything, you can download the most updated version, which matches with your server version here: SQL Server Drivers | Microsoft Docs
I should see the interface where the connection is created, sometimes you must specify SSL as a different checkbox, sometimes using certain ports implies the use of SSL. Without having it in front of me, or know which port should I use it's impossible to say.
I suggest you to check the Advanced options of the DSN and check with your database administrator or IT team who can help you setting that up correctly. Again, not having the driver interface in front of me I cannot guess where that SSL property is
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