C2 accepts only standard minilots (10,000 currency units).
So:
The smallest quantity C2 trades is "1" which is a mini-lot. Thus, the smallest trade a strategy manager can type into C2 is:
BUY 1 EURUSD (for example)
which will trade 10,000 Euros.
No fractions nor numbers smaller than 1 are accepted by C2.
When subscribers use C2 AutoTrading to trade a strategy, and they select a small trade-scaling percentage which in theory would result in some fractional trade below this minimum, trades will instead be placed at the smallest possible quantity allowed. Typically, that is one minilot.