In 2018, Weebly was acquired by Square, which affected the way newly created Weebly stores connect with Easyship.
Our integration with Weebly was built before the acquisition, and only old stores will be able to connect with Easyship on the Weebly app store. For confirmation that this is the case with your store, feel free to reach out to the store support and ask them if an integration can be made with the Easyship app.