Minecraft dungeons for free bug

Update: Sorry, my friend bought minecraft dungeons for me, and he didn't tell me, so i thought it was for free. (I am really sorry that I wasted your time)

I have been exploring new minecraft launcher, and when I went to minecraft dungeons page, there was a download button. I thought it would be free to download and then pay to play, (I haven't bought minecraft dungeons before), so I have downloaded it. But when I opened it, I could play it for free. Is it some kind of free demo? Also, it may be a microsoft store bug (or it isn't a bug at all, but it's a microsoft store feature).