TOTY Edition missing content

I finally found a solution for the problem in case the issue occurred when you bought the game on Steam. You have to redeem the content first. Either there is a button to redeem it next to the Play button in the Steam library, or you can use this link: https://store.steampowered.com/account/claimentitlements
With this it worked for me.
Still disappointing that that is not mentioned anywhere (at least I could not find it), and the support just said I am not eligible instead of mentioning that.
Hope that helps you too if you have this issue!