Hi @SchizofreniQ, In order to play the game on Steam you either need to either purchase or redeem a code on the platform. Players who previously purchased the game on the Microsoft Store platform were not provided codes for the Steam version because the current client features crossplay between the Microsoft Store version and the Steam version. If you need help upgrading the Microsoft Store version to the crossplay client, please see these instructions.
The Steam version of the game is currently 25% off on the Humble Bundle store for another 2 days 21 hours if you would like to purchase it for less than full price. There will likely be future sales and giveaways where you will have an opportunity to receive a copy of the game on Steam at a higher discount as well if you’re willing to wait.
As far as finding games, you may find better results in the unranked lobby. I often see a handful of available games there.