They have worked on something for Zorin 18. Normally when You install Firefox on an Ubuntu-based Distro, You get the Snap Version - even when choose the APT Version - when the Mozilla-own Repo isn't added.
Now, it is so that the Zorin Team will make a Workaround. When You install Firefox as APT in Software Store, You should get a Window like this:
So, this adds the Mozilla Repo and then You get Firefox as .deb Package.