Why am I always kicked out of alliances for not contributing?

The rankings don't do a whole lot. if you're being kicked out of an alliance for not contributing, what that means is on the alliance page there is alliance technology, tap on that and find a technology that you can donate resources to which will progress over time and help everyone in the alliance get buffs when it levels up that technology. But if they're kicking you and not explaining how to contribute, they're not worth being in an alliance and helping new players. Just keep trying to join someone and ask in the alliance chat with how to do something. the more you know then the more people you can help along the way.