What can i do?

Pretty sure you can just Request new winner and have the reason be other and use that reasoning, or use that you can't unable to contact winner through steam or email.

Since he is ignoring your friend steam request, send a reroll request with that explanation, and a link to the description where you explain he has to accept the friend request in the first place.

You'll have to wait until a week after the giveaway's end if you want to use the "couldn't contact winner" reason to reroll.

As for getting a winner who plays wins, there's not much you can do besides make a group-only giveaway for those groups that require winners play their wins, like Playing Appreciated (but for this particular case, it's too late for that unless you're okay with taking a Not Received and redoing the GA entirely).

Your giveaway ended one day ago. The winner has seven days to claim his win. So give him some slack and maybe try to contact him via email.

It's only been a day, you should wait 7 days before making a ticket. And "reading descriptions" isn't a rule, you're better off doing that for groups like Playing Appreciated or Playing Matters.

It looks like your GA only ended 1 day ago, so unless you can show that the winner DECLINED your friend request, you may need to wait a bit longer before support will grant you a reroll. You have to allow the winner 7 days to respond/claim the gift before you can request a new winner.

As for your requirements on playing the game, it is unlikely that support will reroll for that. There isn't a way to really enforce things like that in a public GA, unfortunately. If the winner does accept your friend request within the alloted time frame, you are obligated to give the the game or else accept a "not recieved" feedback. In other words, you aren't allowed to deny a winner the game just because you don't like their profile (you are free to blacklist them after the fact, if you wish).

For the future, I'd recommend setting a higher level for public GAs. The bots and card farmers are still very common at level 1. They seem to drop off quite a bit around level 4 or 5. You can also look at joining a group like Playing Appreciated that requires members to play their wins. There will still be people who grab games and run or just put in the bare minimum to not get kicked out, but you've got a higher percentage of getting your games played.

Making giveaways using sgtools might also be worth a look. I haven't used them myself, but a lot of people like setting up GAs that way since you can create custom rules for allowing people to enter.

Good luck!

Thank you all for your replies and advice I will take it all to heart.
What will happen to me if I get a "not received" feedback?

Most people don't read the giveaway descriptions and even if you request them to play it if they win, they don't have to as there's no requirements to win the game. The winner has 7 days to claim the game after the giveaway ends and it's only 1 day so far, so they have plenty of time to accept your friends request and claim the game. You can leave a comment on a giveaway they created mentioning that you are delivering their win via steam so they'll need to accept the friend's request you've sent them on Steam.

Playing Appreciated is a good group where the winners play the games they've won in 30 days. It might be worth checking out for any future GAs that you would like the game to be played.

I 100% recommend giving away through the group Playing Appreciated. I used to give away games and only one in thirty would actually be played. Since giving away through them, about twenty nine in thirty get played. So I use them exclusively now.

https://www.steamgifts.com/discussion/qNorC/playing-appreciated-giveaways-with-the-intention-for-the-games-to-be-played-within-a-month