Up until recently i thought of myself as a neurotypical person who just happened to find ADHD content relatable. How dare I, a run-of-the-mill idiot and fuck-up, appropriate a real mental disorder in an attempt to explain away all my flaws?
Well anyway it turns out I have ADHD. So yeah, everyone may relate to these things every once in a while. But if you're reading this and you find A LOT of these things relatable, and they happen often, and you can think of lots of examples of times they have caused you major problems, and you feel a lot of shame and guilt and anxiety about the whole thing, I would encourage you to get checked out.
I think you have to ask yourself why he picked out this book. You can even try asking him how he heard about it, if you can do it in a curious non-judgmental way.
If you think he chose it because he wanted the team to improve or grow in this area and the title sounded like a good fit, you can probably be more honest with your criticism, especially if you can offer other theories or strategies and recommended the sources you learned them from. In this case, I think he'd care more that his book triggered these discussions than whether it was strictly any good.
But if you think he has read and enjoyed this book himself, or that he saw it advertised on LinkedIn and thought it would be a nice manager thing to get it for everyone, I think you should keep your comments more positive. Tell him about any parts that you did think were good, point out the topics that you're most interested in researching further, tell him about any ideas for the team that were triggered while reading, etc.