You need to create an acf/save_post filter https://www.advancedcustomfields.com/resources/acf-save_post/
In this filter you need to get the value from the field and then find the correct “category”. I don’t know what this field contains but you should be able to get the term in some way. Then when you have that you use https://developer.wordpress.org/reference/functions/wp_set_post_terms/ to place the post in the category.