@CthuNoCold The missing DLLs may be coming from a seperate download the game should kick off when installing it from the windows store.
Converse with fellow players
Change the permissions of the files it explicitly complains about, that fixed it for me!
I seem to not have been the nly one running into the issue of "LastError: 1813" and complaining about the file otp_notice_na.rtf, as seen here https://lowee.de/2020-05-27_14-23-37.png and followed by the launcher going into a loop, erroring out again https://lowee.de/pso2launcher_2020-05-27_14-16-11.png
I was able to get out of this by (temporarily) disabling Windows Defender AND specifically changing the File permissions for "C:\Program Files\WindowsApps\Mutable\100B7A24.oxyna_126.96.36.199_x64__wyfsmff9ynw7j\otp_notice_na.rtf" as well as pso2.exe - THIS FOLDER IS A LINK TO YOUR ACTUAL INSTALLATION DIRECTORY! So it doesn't matter if it's actually installed somewhere else.
To update the permissions, you first need to take ownership of the files and then add your user to the list of permissions. I also did this for the data subfolder and its contents, but i don't think that is necessary.
TO DO THIS:
Repeat this for any files the launcher may complain about.
Hope this helps!
See you ingame~!
German here, got the same issue.