reinstall Mac OS not offering the correct version

I have a MacMini late 2012. It was running Mohave before it the old drive failed. I've replaced the drive, and am attempting to reinstall the os. When I do a "Command-R" startup and select the reinstall Mac OS option it only offers me Maverics. So I installed Maveriks thinking that I would have to go through an upgrade to get to Mojave. But now I cannot seem to get Mojave anywhere. Ive gone to https://support.apple.com/en-us/HT211683 and clicked through to https://apps.apple.com/us/app/macos-mojave/id1398502828?mt=12. The link to Safari only shows a "Preview" and in the AppStore the "Get" button is greyed out.

What am I missing. How come I can't download the installer for Mohave or more importantly, how come I done get Mohave on reinstall?