The question is in the title. I would like to play the classic BG2 complete; that it is included *now* for those who buy the EE is said on the store page. I already own the EE, which I bought years ago, and it does not include the classic version. However, I cannot buy the EE again for myself: the store only displays the option to 'buy as a gift'. What should I do?

Found it. You have to go the the library *on the website* (not in the app), find BG2:EE, click 'Downloads', 'Serial keys', and then redeem the ket.

Thank you for this! I was wondering why it wasn't in my downloads!

:)

sorry but I want to ask that I can't find Serial Ksys in the Downloads,

Go through GOG website (Not through Galaxy)
Downloads>More>Serial Keys (see attached pic)
In Serial Keys it will say: Baldur's Gate: Enhanced Edition: with a link you copy and paste into your browser to have the original version added to your library.