Song Fei here from Trackingmore App which is a tracking app developed for Shopify.
Are your tracking page generated in aftership's website? They also developped a app for shopify store. You may want to try that app.
And aftership is not your only choice. Trackingmore app will generate a tracking page under your domain and embedded in your website.
The tracking page URL will be https:www.yourdomain.com/apps/trackingmore
The design and layout of your tracking page will follow the settings of your theme as the default.
So when customer track their order, they won't leave your website.
Here is the address for tracking more app: https://apps.shopify.com/trackingmore?utm_source=shopifyforum&utm_medium=forum&utm_campaign=songfei