Well, I only install extensions via the automatic option through the website, I don't do manual install cause I never figured it out. Again, this is one of the areas in which I hate Gnome, cause its unnecessarily difficult for no reason.
But here's the good news. The Zorin brother's are working on Zorin OS 16 LITE right now as we speak. Were hoping they will finish and release it by next year, hopefully soon if were lucky. If you would like, you could ride this Gnome wave until then. And then once LITE is released, you could switch to that for an easier life.
Anyways, just a suggestion, not telling you to switch, just letting you know, it will be an option in the future. We all know XFCE is less painful then Gnome just in general, so might be worth your time installing, when LITE is eventually released.
I got this little puppy installed in my computer right now, its sitting with delicious 1TB of unnalocated space, waiting for OS 16 LITE install.