Navigate to the My Members section and select the Subscriptions tab from the navigation on the left-hand side:
Click on the Add Subscription button to create a new In-App subscription:
Fill in the required information in the subsequent form:
ITC-Product ID: Add the ID of the subscription created in your App Store connect account
Google Play Product ID: Add the ID of the subscription created in your Google Play Developer account
Name: Add a name for the In-App subscription
Description: Add a description for the In-App subscription
Duration: Set the subscription term for the In-App subscription
Appkiosks: Select the Appkiosk which should display the In-App subscription
Click on the Create button after completing the form to create the In-App subscription in your account.