The Microsoft version of the game won’t load or let me play at all.
The error it gives me is
We know you really want to get started, but you’ll have to wait a bit longer. Check the store for the launch date.
The game is out right now and stream and Microsoft have the same launch time ?
Hi, finding the beta on the MS Store is a bit ‘convoluted’. There’s an FAQ on how to find it
If you preordered the game you can download the pre-order beta this way. Note if you’re getting the game via Game Pass for PC/Ultimate, you aren’t eligible for the pre-order beta.
If you refer to the FAQ there’s 3 different apps. You’ll notice the one on the right is has “Pre-order…” in the title. find that one
Basically go to the Darktide page which is what is in your screenshot
Scroll DOWN to the “in this bundle” part of the page
The icon on the right is the “pre-order beta”
You can try to directly get to the page here by using a browser, though tbh the ms store is kinda wonky on the best of days. So I’m not 100% sure if this works
Gosh its so hidden…
So I had to search for dark tide and scroll down then look for the Pre-order beta icon…
Then I could see the install icon >_>
Yeah that’s the one you ened to install
yes its super hidden and not very obvious 
