This guide assumes you have the WooCommerce Shipment Tracking extension installed
To start off, you'll need to check your Shipment Tracking plugin version, you can do this within your Shiptheory account by going into your WooCommerce settings.
if your Shipment Tracking Version is 1.6.18 or later and your WooCommerce version is above 3.5.x, you can select V3 as your Tracking API. If you do not meet either of these requirements, you'll want to look into what version your Shipment Tracking extension supports, but in most cases you should be able to use V2.