Glancing at your scenario, it looks like you're following Adobe's AUSST instructions linearly, since you didn't mention setting up IIS. That's step two, but near the bottom third of Adobe's instructions.
It will get you mostly there. There are a few inconsistencies. The blog only mentions the override in programdata, but Adobe wants it under programdata and program files (x86). Since Adobe's documentation was last published 4/15/2019, I assume its information is more up to date, even if I had to manually create paths.
Both instructions left me lacking an updaterfeed.xml file. I had to include the --legacyUpdates switch on an incremental update to generate that file. Documentation was supposed to have been updated after March 13th, but I couldn't find mention of it.
However, the instructions from the above blog are linear and step by step.