Posting a fb post on a group as *dynamic profile*

Hi, i have a real estate website when people can register and submit their properties. (that’s my staging website)

i made a frontend form to submit a property, my flow looks like this:

first i used webhook to get the data from the form, then i used the facebook group module to post the property in a specific group, and my question regarding how can i control who is posting the post?

in this windows i can only choose as a user or as a page

i want the post to be posted by the real estate agent face facebook account who is submitting the property and not my personal facebook user account

how can i achieve that?