How do I continue the download of Catalina on my mac
The download of Catalina on my MacBook Air stopped because I had to free up more space, so I did, but now I don't now how to continue the download
MacBook Air
Go back to the App Store and try to download it from there.
If you see that it is already installed, look in your Applications folder for a partial download. If it is a partial download, delete that and try to install again.
If it is an app named Install macOS Catalina, run it.