I’d leave the ADHD mention til after you get the offer if possible. Bringing it up in an interview could cause the interviewer to prejudice against you, compared to other candidates who don’t have it (the bonus if you bring it up after receiving the offer, they may have to make reasonable adjustments depending on the laws in your country).
Naturally don’t mention weaknesses that are prerequisites of the job. Instead, maybe say something like “presenting in front of people has never been by strongest point, however I’ve worked to improve this weakness with X example, Y example and Z example (eg taking presenting courses, performing in public, examples of past presentations, etc.).” That way you can talk about your other positive experiences, and give the interviewer an impression that you’ll bring him solutions to problems, rather than just more problems.