Lloyd, I know you're on this other thread, so just posting here for others that stubble onto this thread:
Solutions in https://forums.autodesk.com/t5/civil-3d-forum/storm-and-sanitary-analysis-install-failed-error-15/m-...
There are new builds up today that resolve an issue with a third party component blocking the install of SSA. SSA 2022.0.2 hotfix and SSA 2023.0.1 hotfix are full installs that don't require an earlier version to be installed first - but you also don't have to uninstall an earlier version if you do already have one installed.
Please let us know if you still run into an issue. Sorry for the inconvenience this may have caused.
Charlie Ogden, PE
Product Manager