Never traded CFDs, but I would be amazed to see 100% margin provided with nothing backing it, and if going long, where is the interest being drawn from with no money in the account, also where do the losses come from ... if no money in your account ?
Most people trading are expected to lose. I take pride in being a very good loser, it is about being a manager of bad trades.
So they are basically saying put up or shut up ... it's their rules ... which sounds fair for all the other traders with them, so no individual or individuals blow up to their detriment ... I would actually be grateful that they have such requirements in place, if joining them.