C2 does not impose a minimum account size since as an investor, you can subscribe to a strategy and set your own AutoTrading configurations.
Each strategy has its own Minimum Capital Required. This can be found on the right side of the strategy detail page under the Statistics section. The Minimum Capital Required is calculated by an algorithm that looks at the past 6-month trading activity for the strategy. The result is the smallest amount of capital you can have in an account to allow you to trade a strategy using a small Scaling Percentage without triggering a margin call or receiving a rejection notice due to insufficient funds. Traders who have more or less the minimum capital required can still autotrade the strategy while adjusting their scaling percentage accordingly.
Funding Minimums vary between brokerage firms and which trading instrument you would like to AutoTrade. You'll want to check your trading style and that of the trading system to make sure that you have enough funds to cover positions according to your AutoTrading permissions. Too little funds will trigger a margin call. Again, it all depends on how you would like to trade and how much you are willing to invest into trading.