How can I concentrate in studies over 4hour+?

A good night of sleep, stay hydrated (aka don't drink more than 2 coffees 😆), whatever you study, divide your tasks into sub-tasks so you see your progress, and quite frankly... take breaks!

take breaks and do time boxing

you can find playlists on youtube. Music really does help. Also having a calm and quite environment

I would be eager to learn this too :)

I'd suggest study in chunks, instead of 4 hours straight

Changing subject focus every hour