This article will outline what the order capacity feature is used for, and how to control its settings to best fit your situation.
Order capacity is used to automatically pause your vendor site when the amount of open orders reaches a certain number.
1) This setting is found under the vendor site. Click the "Vendors" tab on the left side. Then the pencil icon of whichever site you are setting them for. 
2)Click the advanced tab and use the Order Capacity Settings text fields to set a maximum and minimum number of orders.
* The top field is where you will enter the highest number of orders that should be open at one time. This number includes orders in all stages except delivered *
* The next field is the unpause number, so how many orders are allowed to still be open when the site is unpaused and able to begin accepting orders again *