I downloaded the latest windows version and when I try to launch the app, it just won't start. I tried running it as administrator and I tried making a shortcut but that didn't do anything. The previous version I had (1.5 I think) worked completely fine with no issues at all.

v1.6 added multiprocessing, which converts all of the tracks in parallel. It speeds up pack generation dramatically when it works, but it hasn't been working for a lot of people. I just released v1.6.2 to fix some issues with it, try that and see if your problem goes away.