downloading Catalina 10.15
I'm currently on High Sierra 10.13.6 on my late 2013 iMAC 27". I tried to download Catalina 10.15. but I see it isn't available anymore. So then, I tried to install 10.15.4 and it told me I need to install 10.15...how do I get around this conundrum? Any help is much appreciated
iMac 27″, macOS 10.13