Hey, happy to know you're interested! :)

So from what I've tested the project seems to work with more recent Unity versions as well (it was coded with Unity 2020.3 btw).

But if you want to be sure, you can always get the Github repo (https://github.com/MinaPecheux/UnityTutorials-RTS) - which is completely free! - on your computer and try the project with the Unity version you want. And then if all works as expected, consider getting the book for more details on how everything works ;)

Hope it helps, cheers!