When talking to a candidate about their limitations, the key is ensuring that your words do not demotivate them. While you have to underline that they are not up for the role, you can also try to help them achieve the requisite expertise. You can suggest skills that they can work on to help them draw a development roadmap for the near future. Candidates will appreciate such help.

Applied online, was contacted via e-mail to set an interview about a week after applying. Had one interview (basic sales questions and salary expectations) with District Manager and two days later he called me offering a job