Nobody is blaming you for anything. It's just sickening that these parasitic "services" like tvgeek exploit the naivety of new users, rinsing them for "services" they could obtain for free if only they knew.
The original addon developers provide the addons for free then these sites bundle them together in an often dysfunctional build and sell to ( dupe) new users.
Follow crowruins advice above. I would only add to that you must allow "add-ons from unknown sources"
Once you've updated to Kodi 18.9 you'll get a prompt or you can access the settings "cog" then to "system" then scroll down to "add-ons" "unknown sources" toggle on.
Then install from the reccommended list he linked.