MapPress requires that each map be associated with a post. But I think Gravity Forms will automatically generate a post on the backend with the data you enter, is that correct?
I think they also save the entered data as custom fields.
If so, you can use the MapPress ‘geocoding’ settings to generate the map in that post from those custom field values. For example if your form includes a field ‘address’ then use that field in the geocoding settings.
I’d suggest configuring geocoding and creating a post manually from the custom field(s) to test that it’s working. Then try sending in the same fields from GF to generate it.
There’s some additional information on setting up geocoding in the documentation.