I certainly understand the frustrations with having to work with an old OS - even Windows 10 will be old news soon!.
In any event, it looks like you ran into problems when applying any outstanding Win 7 updates - step 4 of the instructions.
Although Win 7 is no longer supported since Jan of 2020, I believe that updates made since the original release of the OS (or since Service Pack 1) are still available for download to any activated / licensed copy of Win 7.
I just tested that theory by loading a copy of my DRB III emulator installation on to a Virtual Machine instance of my desktop. I enabled all my network interfaces and initiated Windows Update. It seemed to work just fine (see attached screenshots). Enabling network access may have messed up this instance of my emulator, since you shouldn't have internet access after step 23 but this was just a test to show that Windows 7 updates are still available.
If you were unable to install any Win 7 updates after installing the original OS, I'm not sure how proceeding with installation of all the other components would behave.
You may need to start over again and don't go any further until you figure out why you aren't able to apply any Windows updates per step 4.