OK, I tried installing the CADS Rebar Extension the other day since placing simple rebar has gotten so much harder in Revit now, and ran into errors that their support said were tied to not having this hotfix installed. So I took more time out of my billable hours to deal with this Autodesk bug and find a solution myself. In my previous response with screenshots of error messages, you see that the installer is looking for a dll file in the C:\Autodesk\CF\AdShared\en-US folder. For me, there were 2 other dll files without sufficient privileges, one in that directory and one in the AdShared parent folder. The 3 files were AcAuthEntities24res.dll, AcAxDB24res.dll, and ACSignCore16.dll. But upon reading the error message again, I realized I hadn't seen any "CF" directory in C:\Autodesk. Sure enough, it's not that the installer has insufficient privileges - it's that the hotfix installer is looking for files in nonexistent folders! They exist in C:\Autodesk\Revit_2022_G1_Win_64bit_dlm\x64\RVT\CF\AdShared\en-US, but the installer was looking for them in C:\Autodesk\CF\AdShared\en-US.
After manually creating the folder tree C:\Autodesk\CF\AdShared\en-US, searching for those files and finding them in the Revit 2022 install folder, and copying AcAuthEntities24res.dll and AcAxDB24res.dll into the en-US folder and ACSignCore16.dll into the AdShared folder, then the installer finally installed the hotfix successfully. It still hung up on 33% for quite a while so that I assumed it wasn't going to work again, but then it finally moved on to 100% and completed. Now, versions of the first 2 files were in all of the regional install folders for Italian and Japanese and Spanish and English, and so on, so I used the files from the American folder (en-US); I would guess that anyone having this issue in other regions would need to use the files from the appropriate regional folder (jp for Japanese, fr for French, etc). The third file was common to all regions.
Hope that helps others, and you're welcome, Autodesk. Now where exactly do I send my invoice for my newfound IT skills, Autodesk? 😉