i just started some designs and watched some tutorials online, but i can't find the pathfinder/combine function. And i can't find the function to mask like it's shown here: Adobe Experience Design (Beta) Help | Combine and mask objects
Is there something wrong with the version that i'm using?
Which OS are you running on? There is a difference currently between the Mac and Windows versions in what features are available. The Windows version is behind, since development on that platform started after the Mac version.
As Chris W. Griffith mentioned, it's still a feature in progress. You can upvote for it here to get progress:
I'm using Windows 10. Okay, then i hopefully just have to wait.