Linking / attaching a Creator form entry to an Opportunity

Linking / attaching a Creator form entry to an Opportunity

Hello :)

I created a Creator App (Order) which has a subform (items). I added this App as a Custom TAB (not a web tab) to our CRM.

Now I'd like to "attach" / "add" specific entries of this Order form to our CRM Opportunites. How could I achieve this ? Must the app be as Custom tab, or can I Attach / Link From Creator to Opportunitis directly ?

Thanks