Hello,
See if this reference helps : https://docs.gravityforms.com/category/getting-started/add-form-to-site/
Also, as Gravity Form is the premium plugin there should be their dedicated support which can unblock you quickly. Ref: https://community.gravityforms.com/
If you’re asking about using the HTML content field and entering it that way, I don’t believe it works. The reasoning behind that is each form field gets processed by the plugin for inclusion in submission, adding to notifications, writing to the database, validation, etc…. Since you created a custom form input inside this section it missing all that processing
In theory, any input inside a form should get passed through during the submission process so you should be able to get at it somewhere. I don’t know which hook you’d use though but one of the submission one I expect are what you’re after. Once you find it though, it is mostly on you to write some code in order to handle this input and have it treated like the other fields
