Cannot download Catalina from App store
I have a late 2014 Mac Mini with sufficient memory and space to run Catalina. Currently I am running 10.11.6 El Capitan. I want to upgrade to Catalina. But whenever I try to download it from the app store, it only downloads for a short while and then nothing ever appears in my downloads, or on my desktop, or anything I can do to install Catalina. It seems like nothing is being downloaded at all. Where can I get Catalina? Do I have to upgrade to Mojave first?