To activate Disney Plus on your mobile device, start by downloading the Disney+ app from the Google Play Store or Apple App Store. Open the app and sign in using your Disney+ credentials. If prompted, you may need to enter an activation code by visiting disneyplus.com/begin on a web browser. Enter the 8-digit code displayed on your mobile screen and click "Continue." Once verified, your mobile device will automatically activate, giving you full access to Disney Plus. Make sure your subscription is active to stream your favorite shows and movies instantly on the go with Disney+.