In order to start using Shiptheory, you will need to setup the Shipping Options to Shipped by Seller (non-platform shippping).
First goto the Seller Center and to the left find Shipping > Shipping Options
Locate Shipped by Seller in the next page, and press the Set as Preferred to complete the setup.
The TikTok platform may ask you to create a Shipping Fee Template if you have done so. Click on the "Manage shipping fee template" on the right. In the next page, click "Add Next Template".
In a shipping fee template, you can setup how much you charge the customer based on region, shipment weight, type of service etc. A sample was given below.
If you have not setup your warehouse address etc, you may want to do so. After all, you are good to start shipping with Shiptheory.