I have an WordPress installation that, for some reason I did not do using Softaculous Auto Installer. Is there any way, without reinstalling it, that I can get Softaculous to pick it up?
You can import your installation to Softaculous and them manage the upgrades backups etc via Softaculous. Here is the guide on how to import your installation to Softaculous :
https://softaculous.com/docs/How_to_Import_an_Installation