I have Mojave 10.14.6. I can not download Catalina to upgrade. Why?
Why can I not upgrade my IOS to Catalina 10.16?
MacBook Pro 15", macOS 10.14
Catalina is 10.15, ok, what have you tried. Connect your Mac to your router using a cabled connection,
don't use the Mac whilst it is downloading, restrict other devices from sharing your internet connection.