I started learning music as an adult too a few years ago in the local community college. Especially initially I couldn't trust myself at all with playing, rhythm or anything, so I ended up hacking on some exercises, as new concepts appeared. See if you can find them helpful. They turned out pretty useful with students and teachers in my college.

Some are simple intervals and stuff that other more polished apps do better, but some are more advanced and I've not seen anywhere else.

E.g. ear training for more complex chords (9, sus, 6/9) https://www.onlinemusictools.com/chords/

Or interval "strands", a regular interval training but with three notes, which looks like it should be simple but is a big jump from 2-note intervals: https://www.onlinemusictools.com/strands/