An interview with a client is taking too long.
While it is not customary for interviews to be paid, if the interview is taking too much time, you can suggest the following:
Hi [client name], I would like to be compensated for further time I spend working / interviewing with you. Can you please “Hire” me as a contractor first via LD Talent, if you are interested in working with me or interviewing me more via more hands-on methods?