For the application to work properly, you need to change the store shipping settings. Go to Settings, click on Shipping and choose Manage rates.
You should add different weight-based shipping rates under each country where you are planning to ship with Parcely app. To do so click on “Add rate” button and add free shipping with weight from 1000 kg to 1500kg. If you would that your customers would see only shipping option what they already selected in cart view then add different weight rates for each shipping option which you are using.
PS: don’t forget to change Parcely “Delivery” product variation product weights to match your shipping zone rate weights.