There is no application set to open the URL macappstore://showUpdatesPage?scan

I partitioned my iMac to keep old version. The new partition has no operating system. I don't have the usual update in preferences, but I don't care about updates, I need upgrades like Catalina to start using the new partition to eventually move all my data to it. I checked the criteria and this iMac is good to go, if I could ever find the real download button for these old OS versions as well as Ventura!

That's a lot,

thanks, Cheryl