The other day I went to play War Thunder and the launcher required an update to the game to proceed. I naturally agreed whole-heartedly, without reservation, and let things happen.
Getting towards the end of the process, an error message pops up, saying that I did not have the required permissions to perform certain actions, actions that were never defined.
In the end, I allowed full control over the whole War Thunder folder, and it’s contents, and that solved the issue. If you have the time, you could add Full Control to each user or group attached to the folder (Possibly ‘Trusted Installer’ would actually save the day) one at a time to see which is the user/group that needs the access to the War Thunder folder.