Upgrading from MacOS 10.13.6
I have a MacBook Pro (Retina, Mid 2015), 2.3 GHz Intel Core i7, running MacOS 10.13.6 High Siera. I need to upgrade to at least Mojave or preferably Catalina to be able to use some programs I need, but I can find no way to do this. Several sites including Apple Support say that you can do this from the App Store, but I find no macOS Mojave app or installer to download. The sites I have visited also say that my computer is in the age range where it is compatible with Mojave or Catalina, and I just cleaned the hard drive and reinstalled High Siera (only thing it wold let me instal) again so there is as much disk space as I will ever have. What am I missing or what did I so wrong?
MacBook Pro 15″, OS X 10.11