Maybe Artworks Bethesda? My teen takes are classes there and likes it.

Look into the Gaithersburg Arts Barn in the Kentlands. It's part of the City of Gaithersburg's recreational program. They have small classes for kids, teens, and adults including on the weekends.

Both my teen daughter and I have taken many classes there over the years and enjoyed them (and when younger she did many summer art camps there as well). It may depend on the instructor/class how much flexibility there is, but we've found the instructors warm, encouraging, and flexible. I personally loved the Ceramics: Hand-building classes with artist Yolanda Prinsloo -- she is so creative and open-minded to anyone's ideas and just a joy -- and I found working with clay rather therapeutic for dealing with excess stress!

If it's a bit of a drive to Gaithersburg and you'd have to wait while your daughter is in a class, the walking paths around the lakes are lovely or there are shops close by in the shopping district.

Not many art classes I know of for kids at 15. Many art classes are recorded on youtube. My DD follows along with a woman who paints. Plus it allows her to stop/pause when needed.

Maybe try outschool or Glen Echo?

DD (15, ASD, ADHD) wants to take an art class but school schedule won’t allow week days.

We did VisArts for many years but they don’t have a class she wants that will work for our schedule.

Any recommendation for someplace that is flexible and ASD/ADHD friendly?

She’s super talented in drawing and painting but pretty inflexible (likes to draw what she wants).