I make an HTML tools collection
I put an embed code in a page and try to +add field the custom code from the draft but Code embed doesn’t recognize : Text field or richtexte field or embed code field
I don’t see the Embed on the page you shared.
However it is a collection page, so the Embed should show the +Add Field option if it’s outside of a component.
+Add field can add plain text fields and a few other types, but it can not add Rich Text. You’ll need a different approach for that.