Elsweyr Digital Collector's Edition

I've been looking for the answer to this everywhere and can't find it.

If I purchase the Elswyer Digital Collector's Edition can I add it to my existing ESO account?

I already own the base game and have the Guilds & Glory pack because I was able to get a Gold Edition to my ESO account. Can I do the same here?

I am making the purchase directly through the ESO store: https://account.elderscrollsonline.com/store/product/eso_elsweyr_edition_ce

and it does have the "BUY NOW" button available instead of the "You are not eligible for this product".