There are 2 modes in this extension to update product quantity.
In this mode, you edit the quantity field directly.
In this mode, the value entered will be added to the existing quantity levels.
To enable the addition mode, enable “Add Quantity Mode“
Validation by Ordered Product Option
If this is enabled, then the validation is done based on the ordered product option quantity. In this mode, all options of the product quantity are not validated, and only the option that is ordered by the customer is validated.
If this is disabled, then the validation is done to the product ordered by the customer, and if the product has options, all options of the product are validated.