You can check that your D+ subscription is linked to your WDW account by logging in to your WDW account, then click on "Profile" under "MyDisneyExperience", then click on "Membership and Passes". This will bring you a page that lists all your Disney affiliations, like Canada Resident,
DCL Castaway Club, D23 membership (even the free tier), Disney Visa card, Disney Annual Pass, Disney Main Entrance Pass, whatever applies in your situation (this is also where you can add some of those things if they are not listed)...
And Disney+ subscriber:
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The email address on your WDW account and your Disney+ account must be the same, that is how they link them.
SW