I don't think it should be too difficult to set up and understand what's going on.

Download it, install it, run it. Click on the listed apps to toggle whether you want them to be monitored (toggling this off means the app will be "ignored" by TrackerControl), if they can access the internet, or if you only want to block certain general categories (advertising, tracking, others). Some of the blocked domains that show up on those categories can be allowed by tapping them, the text will display if they're allowed or blocked.

Running it can make some apps not work properly. If manually allowing some stuff doesn't work, simply stop monitoring said app. I have to do this with some shopping apps: i stop monitoring them, finish the checkout, pay, turn monitoring back on.

If you already use a VPN app, then TC won't work, since it acts as a "local VPN"

I hope this response was useful and helpful. If not, please do say so and I'll try to make things clearer ;)