Servus, Helmi! Great to see you are interested in Discourse for Teams. It’s still a fairly new product so I’m not surprised you didn’t find out about it if you haven’t been hanging out actively here on meta or following us on twitter!
Discourse for Teams is a hosted product built with Discourse. If you wanted to set up your own self-hosted Discourse and invite your slack communities over, you’re welcome to do that - Discourse is open source and is very configurable. But of course you have hosting costs and the effort of customizing and running it for all those comunities.
The advantage of Discourse for Teams is that it is quick and easy to spin up a site and get your team invited and collaborating. We also intentionally priced it so it is affordable for small teams. So you could conceivably talk with your slack channels about moving to Teams.
Feel free to spin up a free trial, and PM me if you want to brainstorm about specifics for moving your slack communities over. In case you missed it, you might like to take a look at Comparing Discourse for Teams with Discourse to learn more.