A sort of pair of invisible windows open after pressing start, if you didn't get the connection error then you're in the right proton, Experimental might work too. It might seem like nothing happened after a small loading animation however, by minimazing and reopening the window in desktop mode you are able to catch a glimpse to what it says; First is the login method, click on Steam, this one was easy to do. However the second is the user agreement, scrolling down with the mouse wheel sometimes makes it flash which makes the window visible for brief blinks of a moment. this one took me a bit of time, but I recorded on my phone as the window would flash visible to see where the buttons to "agree" are located (it doesn't help that it's in chinese lol) But like i said, the window is only invisible but the buttons are definetly there, so just click where you think you saw it. after the login screen, it's smoth sailing, and you auto-login any time after that so it's only a one time deal.

The only bug i've found is that the initial lore animation videos are completely black, audio works fine but you can't see anything. you can skip them though and the rest of the story is visible normally