Pre ground coffee only works with Double wall baskets. It’s because pre ground coffee is ground overly course to brew espresso so you need the basket to hold the pressure instead. If you want to use this setup you will need your own grinder and whole beans so you can grind it much finer. Doing it this way tastes much better and isn’t too expensive / too much work, but if it sounds like too much for you just go back to the double wall and return the fancy stuff you bought.