Snap is available for Linux Mint 18.2 (Sonya), Linux Mint 18.3 (Sylvia), Linux Mint 19 (Tara), Linux Mint 19.1 (Tessa) and the latest release, Linux Mint 20 (Ulyana).
You can find out which version of Linux Mint you’re running by opening System info from the Preferences menu.
Mint info
On Linux Mint 20, /etc/apt/preferences.d/nosnap.pref needs to be removed before Snap can be installed. This can be accomplished from the command line:
$ sudo rm /etc/apt/preferences.d/nosnap.pref
$ sudo apt update