I bought the game but I have an issue downloading it...

I bought the game from the Uber store but I changed my key to a Steam Key before I downloaded the game. I have linked my Ubernet account to Steam but I don't know where to download it. Any ideas?

If you activated your key in Steam you need to run it though Steam, isn't it in your Library?

Nope :/

Try to activate Steam key again and if it's saying it's already activated you probably need to contact Steam support. I also know that some people fix that problems by removing their local steam data.

You can also open this URL:
https://store.steampowered.com/account/
And check your latest games you bought or activate, if you don't see PA here you definitely need to contact Steam support, but if it's here you might try to fix it with manipulations with your local steam data.

Anyway It's not PA bug, so you need re-check it again or wait for Steam support answer.