This game used to be somewhat enjoyable. Now it's just a chore.
Everything you do in this game is practically punished in the form of its predatory economy. Have you unlocked a new tank after hours/days of grinding research points? Now you've gotta pay your silver lions (the in-game "free" currency) to acquire it. Then you've gotta crew it by spending even MORE lions. And when it's inevitably destroyed in battle, you pay even MORE lions to get it repaired, which is anything but cheap. This isn't even including ammunition or modification costs. In fact, it's extremely challenging for an average player to go positive, even with premium bonuses. As such, it's nearly impossible for a non-premium user to progress at any pace slower than the snail the company represents.
Until a major overhaul of the game is done, don't even bother touching it. You'll only be wasting time that you can be playing something more fun than this.