This article in ShippingEasy's knowledge base explains the steps to take to export your products to a CSV file.
The CSV you export can be mapped and imported into GroovePacker directly but there are a couple of differences worth noting that call for special attention.
GroovePacker uses a separate file to import kit data. ShippingEasy includes the kit data in the products data csv. This means that kits will not be recognized properly in the csv exported form ShippingEasy.
The workaround is to leave the kit SKUs out of the product export and create an mock order in ShippingEasy that contains all of your kits. When you import this mock order into GroovePacker it will create the kits automatically.