Ahoy there! For some of you who are first getting into Sea of Thieves on Steam, I just ran into a major issue while setting up my girlfriend as a new player, and I wanted to post a solution in case any other players run into the same issue.
After installing and launching the game, a little window pops up that says "LET'S GET YOU SIGNED-" Well, that's all it said. The rest of the text was cut off by the edge of the UNRESIZABLE window. Using a third party application to extend the window even failed to display anything further than the cut text programmed by landlubbers.
I ran through a lot of other threads, telling us to uninstall and reinstall and deinstall and log out and log in and download and upload and sideload and blah blah blah Xbox app and some other shenanigans. Nothing worked, because the solution was much more simple.
Just because the P00P DECK SCRUBB3R who programmed the window didn't allow you to resize it doesn't mean that the buttons aren't there. Press TAB and then press SPACE. It will continue to the next page where you will be allowed to log in to your Microsoft account, despite the cropping being about as useful as planting palm trees in Antarctica.
Hope this helps some other pirates trying to set sail!
References:
How the log in process is supposed to go
Images:
Your screen should look like this:
But it may look like this:
So pressing TAB and then SPACE will allow you to activate the hidden sign in button here:



