Um... 100 euros? I think I'd rather wait for somebody to do a video on it. Sorry :/
I use Ubuntu 15.10 (64 bit).

OK, I'll try that.

Tutorials never work. I've learned that the hard way. There's always something that's different for you from the tutorial's creator.

Okay, I wasn't going to mention this loud and clear, but I'm getting annoyed by it;
I'm sick of packs that took >5 minutes to make getting more upvotes than my hard work, Ze Beginner's Guide.
I mean, just look at the Hot tab. The first ~5 levels in that list have over 20 upvotes, and they're all tiny single-leveled packs that are really easy, short and uncreative. And my pack, Ze Beginner's Guide, has 18 individual levels, each of them creative, long and moderately difficult, and it took me a couple days to create it. So why exactly does it have only 19 upvotes?
I found out why; The "Hot" tab. It's the first thing people see when they go into the custom level screen. The hottest levels, with the most upvotes. Of course, as players' nature, they'd click the first level in the list, because it's probably the best. That means many of the players go to the top levels in the hot list, and, of course they won't check out the ones lower at the list, because they're 'not as good'. So they play the first level in the list. Maybe they like it for some reason. So they upvote it. Meaning it's still on the top of the list. But they don't upvote the lower levels, or even bother playing them. So they never get on the top of the list. So all the levels that could be potentially good aren't even played because the levels that are already noticed will keep being more and more noticed, but with no progress on the not yet noticed levels.
So what's my suggestion?
Well, there are a couple ways to solve this problem.
1. Remove the Hot tab completely from the game. It sucks.
2. Reset the Hot tab every day and rearrange the levels randomly when it is reset.
3. Add another tab that the players will be on the first time they go on the custom level screen, that has nothing to do with real-time popularity.
4. Take down the current hottest levels and then do either option 2 or 3.
5. Same as option 4, but instead of taking them down, reset their votes.
6. Reset votes for all levels.
7. Add more voting options, like "Long vs Short", "Difficult vs Easy", "Creative vs Uncreative", "Enjoyable vs Unenjoyable", "Interesting vs Boring" or "Fun vs Frustrating". Then, maybe make tabs that are sorted by those votes.
I'm 100% sure you'll have to take action about this, because this is really annoying me. I don't want my hard work being ignored over small work.

I'm trying but not having much luck so far. Don't really know where to start. VirtualBox seems to work until I actually run the virtual machine.

All packs, except for a couple but I think those are just updated so yeah all.

:( I really want to play it. Can somebody at least make a video of it?

Also, now that I found this fix, I don't really want to sound jealous, but... Conjurer's "Welcome, early birds :)" pack has 50 upvotes, and it just has one really small and easy navigation level, while my "Ze Beginner's Guide" pack which took a couple days to create and has 18 challenging, long and interesting levels, only has 19 upvotes. I feel like that's really wrong.

Oooooooooh, I know what the problem is! Now I realize it. The problem is this; The public vote count updates fine, but when you download a level, the "private" vote count doesn't update. So it just stays the same. If you redownload the pack, it updates.

Done.