In order to redeem your Azure credit (aka MSDN Subscription or better known by Visual Studio Enterprise Subscription), you'll need to activate it at https://azure.microsoft.com/en-us/offers/ms-azr-0064p/. Log in to the BizSpark portal, under 'myBizSpark' you'll see 'Offers'. This is the place where you can assign accounts (screenshots shown)
You'll have to have a valid BizSpark account.
To apply for BizSpark,
head to the BizSpark portal (https://bizspark.microsoft.com). Sign in with a Microsoft account(preferably your email with your domain). Follow through the process. Make sure you select the correct country. Once that's done, we'll have our team here in Microsoft approving (contact us if it's pending for more than 2 weeks).
Welcome to the family 🙂
Note: When you add a new email, there is a wait time for it to change from 'Processing' to 'Pending' to 'Assigned'. Please wait a few hours before activating the Azure portion.