The artbook, ost and poster you get from the gamesplanet.com in "My Games" where your key is, on the right side you will see "Additional download" 2 files - one the packed .bin file and .exe for the instalation of the bonus content. In game stuff you get with uplay client downloaded and after the patch issue resolved by https://uk.gamesplanet.com/community/anno-2070-uplay-key--1451-1/discussions/80083-how-to-stop-the-infinite-reboot-loop

The exclusive premium content (soundtrack, artbook, and reference poster) isn't in-game. The installer for the content is now in the game's entry in your my account page.

Should be available in the game itself. http://images.akamai.steamusercontent.com/ugc/540762066908105286/7D843DCB29D60838BD05A4A5840CADAABA785DD2/