Hey Foundation99,
Welcome to Apple Support Communities. From what we understand, when accessing Apple TV app from Rogers TV device, you're getting a prompt to subscribe to the service, however you already have an active subscription. The information below may help.
Follow the steps below to sign into the Apple TV app on your smart TV or other devices.
1. Open the Apple TV app
on your smart TV or other device.
2. Navigate to Settings.
3. Select Accounts, then select Sign In.
4. Follow the onscreen instructions to do either of the following:
* Sign in using an iPhone, iPad, or iPod touch (with iOS 11 or later), or an Android device that supports QR scanning: Use your camera to scan the QR code that appears onscreen, then follow the instructions on your device to sign in.
* Sign in manually: Select “Sign in manually,” then follow the onscreen instructions to enter your Apple ID.
You can also see the steps here: Get started .
Also, make sure the Apple ID associated with Apple TV+ subscription is the same one you're signing in on Rogers TV device.
If you're experiencing a different issue, provide us more details. More details may help get you more answers.
Take care.