They are talking about the Steam properties for the game (right-click on Tower Unite in your Steam library), where in the “betas” tab you can switch between the default branch and the lowbandwidth branch of the game. However, PAK is enabled by default in the default branch, and I doubt that this has anything to do with the problem. But you could try switching to the lowbandwidth branch anyway, just to be sure.
In case that does not make a difference, could you take a look in your crashes folder inside the AppData folder (
[Install drive]:\Users\[Windows username]\AppData\Local\Tower\Saved\Crashes)? You could also navigate there manually in Windows Explorer by executing
%appdata% in the address bar, which brings you to
...\AppData\Roaming. In that folder, look for folders named something like
UE4CC-Windows-... and see if such folders were created recently, when you last tried to launch the game. If so, please take the most recent folder, compress it into a .zip or .rar file or anything similar, and upload it to a file hosting service such as Dropbox or Mega.nz and share the link in a post here. That way we can look into the cause of the crash. We are sorry for the inconvenience.