I have an address field that must be filled automatically in the wp-admin when choosing a customer name from a selectable field.
This is possible with ACF
This is not something that ACF provides. In order to do this you must add custom JavaScript do does an AJAX request to get the related data and populates the other fields. I have some examples of doing similar things here https://github.com/Hube2/acf-dynamic-ajax-select-example