Minecraft -play account created via IOS also on Windows PC?

My son has a Minecraft account on the Mac, now he has a Windows laptop and wants to continue playing the character there… Is that possible?

So Mac or iOS?

iOS runs on mobile devices (iPad, iPhone etc.), Mac on laptops and desktops.

If he plays it on a Mac, he can continue playing on a Windows PC. If he switches from iOS to a Windows PC, he has to buy the game again.