That's actually completely right. You can't understand WWII without reading about the prior century, especially the history of colonialism.
The chief reason WWII happened was because Japan and Germany looked around and saw a US-Anglo global hegemony forming. The British had pretty aggressively expanded their empire world-wide, killing millions along the way, and were using that as economic leverage to bully everyone else. In the US, well, they did the same thing, but throughout the North American continent, and were beginning to expand globally as well.
Both Japan and Germany, who previously hasn't done much colonial expansion, realized they had a choice of either becoming feudal states to a US/British alliance, or could try carving out their own empires. And, of course, they took a chance, which ultimately failed since they started way too late in the game.
Ironically, the modern EU, now dominated by Germany, is pretty close to Hitler's original vision of Europe, albeit without quite as much bloodshed or ethnic "purity". It's a continent-spanning political system where almost all of Europe is economically and militarily unified under German leadership.
Hitler hated communism, not socialism. The two are not the same. Hitler very much loved socialism.