Ditch what you've been told about parking yourself cross-legged for twenty minutes and trying for a "blank mind." That sentence alone was written by someone whose brain has only a handful of tabs open at once, https://www.themindfulcounselor.me/blog/find-time-meditate.
The ADHD brain feeds on dopamine, novelty, and a stream of sensory information — so the opposite of those things (calm, quiet, repetition) when asked of us, would in most people cause them to feel not good enough — like everyone else would; but also feel like an immense failure. Which, again, does not come from willpower — it comes from using it the wrong way. Start with two minutes.
Don't reach for ten minutes.
Genuinely aim for two minutes instead; which, in the first 30 seconds of which, you are going to drift off in some kind of awesome way anyway; so with all due respect — the less runway you have when it first zooms away, the less time it has to pick up too much speed,and you can bring it back! Success is simply returning —and this is your entire rep. Doing the rep for 50 occasions throughout two minutes,you would most certainly generate more focus muscle than someone who just sat quietly for twenty minutes on the floor,totally disconnected from any thought.
Motion works greatly; meditative walking, dancing, even wandering the house; or anything physical at all while trying to meditate... Anything! Try pacing the house or the room with something tactile and just tune into your breath when it would not be a good situation at all,if anyone in the world were to watch your behavior! Whether you buy it or not... "tidy up the kitchen" meditation (the tap on, hands in motion and mind in its body) is frequently how the most present, intelligent minds actually find bliss with meditation instead of a flawlessly posed, Instagram-worthy, meditative bliss pose.
Sound can be another lifesaver where complete quiet becomes hard to sit with in an ADHD brain. Listen to your favorite meditation recordings, ambient soundscapes, or even just the sound of the clocks ticking in your room and your brain will do the rest by fixating on whatever thing it's listening to!
Timing of this meditation session during your day matters too... If you take prescription medication that you take during the day then this is frequently a much better time than early morning, when your brain is far from switched on.