The "Max Order Size" in the "Account settings" is the maximum number of lots that can be copied for a single order (not for accumulated positions). This caps the order size.
If you set a Max Order Size to 10, the maximum lots copied is 10 if there is enough margin, but, of course, if the computed number of lots to copy is smaller than 10, it will copy only this order size computed.
This value does not work like a filter. It means that if the min order size allowed by your broker is bigger than this max trade size, the trade copier copies the min trade size. In this particular case, the system always tries to copy the trade with the minimum allowed value.
If you don't set any Max Order Size (default), the system copies the number of lots computed using the Risk Factor, no matter the order size as long as there is enough margin.