When ever you have to install snap or snapd then sometime linuxmint doesnot give proper support. This is not any big issue. If you are facing the same problem like this.
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
Package snapd is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
E: Package 'snapd' has no installation candidate
Then you need to follow following steps:
1. sudo rm /etc/apt/preferences.d/nosnap.pref
2. sudo apt update
3. sudo apt install -y snapd
4. snap version
Now You are ready to use snap.