Most people don't use the itch.io launcher and download the zip file from the site. So there is little information about how the launcher effects the folders.
Recently, another user had a similar problem and found the folder at Users\Itch-player\Appdata\Strive. I suspect that the launcher is rerouting the "user://" paths to a different folder, and I don't expect any other troubles besides the buttons not opening those folders. I have a bugfix patch on the Strive Discord #mods channel(https://itch.io/t/284398/discord), which will allow you to set the "bodies" and "portraits" folders to anywhere on the computer.
It will probably be quite a while before the folders work well by default with the launcher.