Cannot apply to existing sites

Templates are standalone websites, so it's impossible to add to an existing site. You’ll have to build out the new site from scratch, copying over content from a previous site to the new template site, and re-adding the domain + hosting.

No "Basic" subscription

Subscribing to a Core, Plus, or Advanced plan is required for all template features to work properly. SM Templates use Custom Code to be able to function properly — if you see styles suddenly change after upgrading, you probably picked the Basic plan.