Now I'm stuck in a loading screen.

You can use the instructions at https://community.bistudio.com/wiki/Arma_3_Dedicated_Server along with TADST to simplify the setup. It sounds like you don't have a config file that is being saved properly. Sounds silly but make sure you are saving the profile that you've configured using TADST before you hit launch. TADST should generate a config file for your server.

You could also try setting up the server without TADST and then add in the use of TADST after you've proofed the server. Just a couple of suggestions.