The OTRS website disadvises installing OTRS on Windows. However, since WSL is essentially Linux running in Windows (and I misread the 2012 as 2016), I thought you might have succeeded installing it this way.

The script uses fork and kill, which behave differently on Windows. fcntl isn't implemented. It would probably be easier setting up Linux in a VM and run it there (if 2016* is "fresh" enough for you, there's even a (third party) premade VM).

* - production year, not Windows version