Hello!
The key for Sid Meier's Civilization V or IV may be used in Steam Client. The activation details are provided in all product pages https://www.kinguin.net/category/4906/sid-meier-s-civilization-v-complete-edition-steam-key/#activation-details. In case of any issues with the products, please contact us and we will help you.
Best regards
Kinguin Customer Support

Took 9 days for a response only after a PayPal dispute was opened, only to get the same copy paste response as before. Useless.

They dont give you a phone or contact details. They just have a livechat where they tell you that they are sorry and some other department they cant contact is in charge of whatever you need.

Scam

As a buyer's protection user, I suspect that if you have a problem with a purchase, the time for Support to reply seems to depend on the price you paid, e.g. if you spend 30+EUR you're bound to pay more for buyer's protection and thus, get Support's attention faster.
With my 2 EUR payment each of my ticket's 4 replies I waited exactly 22 or 23 hrs, while for my 40EUR payment I got immediate and adequate service via chat

Once a merchant sold me a used key and customer service contacted me about it after I left negative feedback to the merchant. They asked me a few questions and then refunded. I wasn't even expecting that when I left the negative feedback so I was pleasantly surprised. They answer fast too.

They are very biased and unprofessional. They treated me like a criminal after I showed them multiple proofs that those gift cards were mine.

I just got with their service within 20 mins of my request. I've seen it quicker too, though I think I've only had to use them 1 other time too.