What you’re trying to do will not work.
acf_add_local_field_group() and acf_add_local_field() do not save any information to the database or files. These field groups and fields will only exist on the page load that runs the code. Since you’re running this only when the form is posted, that’s the only time the fields will exist.
If you want this to be persistent then you need to store the information yourself and then load that information on every page load and use it to create the field groups/fields.
