Advanced Portal by Joomla - Add more fields in the new case creation form

Hi I read a 6 years old post about how to add new field in the case creation form but I need more elaborate answer, I am using Joomla version 3.9.20 with AOP extension, I need to include in the case creation form an additional field that exist in suiteCRM called product that is a drop down field.
If there are some examples. I guess that I need to change suggarCaseConnection.php as well SugarCase, but i don’t know how get the field from suitecrm and how modifye …/newcase/tmpl/default.php .