I too have been faced with this problem. We have 2 computers and thus 2 accounts. On one, the game downloaded easily, installed and runs. On the other, (I don't know if it at all had to do with the internet dropping for 5 minutes at the end of the download or not) but the download was close to done, we lost net, when i relaunched it it wouldn't download and instead gave me a last error of i believe 1813. With some digging, I was able to "rectify" this and the download began up once more. Upon completion of the download I ran into a new error of it saying a vox.dll file was missing that was clearly there. Again, much digging, used some info on powershell, and I was able to rectify that situation. The game now fully downloaded launches to its title screen but won't let me do anythign else. if I hit enter or click it or anything else, you can see the flash of white showing that it recognizes a button was hit, and even sometimes like a mini half load circle thing in the middle of the screen but it never progresses. It never picks or finds an xbox account. I too have the companion app running, registry app, even the xbox beta app. I've spent a day downloading, reading, performing random fixes only to have a game launch that I can't get past the title screen.
P.S. In my program files in windows, it doesn't even show up for deinstallation and the like
Does anyone at all know what is causing this one bug, and/or if they are actually working on addressing it or the many others I've tackled? I just can't understand how the one computer downloaded and installed it perfectly without issue and the other has had absolutely no success.
P.P.S My current test is just copying the entire PSO2 files from the computer that its working on and sending them thru the network to the other computer to see if that provides and sort of difference.