The SISTIC Mall Easyship Integration automatically calculates the shipping rates for the available couriers, based on the physical dimensions, weight and shipping category of the products.
When adding/editing your products, there are essentially 5 attributes that you need to populate in order for the products to be eligible to ship.
Omnyfy Dimension Length (cm)
Omnyfy Dimension Width (cm)
Omnyfy Dimension Height (cm)
Regarding the shipping category, depending on what you select, will determine the price and availability for couriers. If you cannot find the relevant category, you can choose the closest category available.
You can always import these values in using the import sheet too.