I think strwbry has a lot of good tips there. I am college student who was recently diagnosed with ADHD at age 20 and recently passed my personal training certification exam. Studying for that was almost entirely reading and teaching myself the material and I can’t tell you how many times I got so frustrated when reading because I couldn’t focus and absorb the material for more than 10 mins. Strwbry mentioned a few above that I do but I thought I would second them here. I use chunking, in other words I set a timer for a set amount of time and when the timer is over I take a little brain break and then do it again. The key to this is to start your work early and not procrastinate. I also agree with the snacks tip, I always like to have a snack handy or a drink of some sort. I don’t know how it works but it really helps me. I also like to do my work in a really comfy place because then it doesn’t feel like work so I will read my textbook while in bed or on the couch or just any comfy chair.
I wish you the best of luck and hope these help!