In order to create an Adaptive form based on an XFA Form template, you need to associate the template with the form using form model tab. Below document mentions the approach along with the necessary screenshot, please try this and let us know if you need any help further.
I have created a form using livecycle ES3. i have heard that AEM can export the fields from existing livecycle form and create AEM form? Could you please help me on that please?