Help CenterMax Account Position Size and Max Symbol Position Size: if the accumulated position size on the account or per symbol would exceed this value it prevents the Trade Copier to copy new open orders. If you combine Max Account Position Size and Max Symbol Position Size, the most restrictive value will be applied.
For example, if you have defined the Max Account Position Size to 0.5, you will be able to open a maximum of 0.5 lot in one direction either buy or sell, that means that you could have at the same time 0.5 lot buy and 0.5 lot sell at the same time, however you will not be able to open a new trade. In the case you have already a buy position of 0.4 lot and you copy a new trade of 0.3 lot, this new trade will be capped to 0.1 lot in order to have maximum account position size of 0.5 lot. The max position size includes all orders on the account, from any source, not just those created by the Trade Copier.
Read more about Max Account Position Size and Max Symbol Position Size.