Physical book to Dnd Beyond

If you bought the physical book for Keys of the Golden Vault, is there a way to unlock the digital version on D&D Beyond?

Generally, no - the reasons can be summarised as:

• This is a different product, being interactive and requiring programming in independently
• There is no easy way to police it, so one book could unlock hundreds of accounts
• If someone opened the book in the shop, they could use the code without buying it

It's along the same lines as "I bought this game on Xbox, can I unlock it for free on Playstation?". It comes up very often!

If you want both, you have to buy them separately.

Alternatively, you can buy them as a physical-digital bundle from Wizards' website.

The only option was to purchase the Book and Key combo direct from the offical wizards online only store. 

https://dndstore.wizards.com/us/product/810963/keys-from-the-golden-vault-book-bundle

Something to keep in mind for future purposes. 

I would really like to see WOTC coast start to offer the bundles available at brick and mortar stores.