Look, on the right of https://tezos.atticpool.com/ there is a link to Attic pool https://atticpool.com/
On the latter site you can scroll down and you will see "Our team" and you will see Serhii there
Which other confirmation do you need? )) You need to confirm that it's their site? ) You can check whois or may be if it's easier (because you are from Ukraine) - you can get in touch with them by phone or even visit their office)

Especially if the amount of coins you want to delegate is big - yes it's better to check everything.

But also we need to remember that:

Your XTZs never leave your wallet when you delegate them to Attic Pool. At its essence delegation is just giving a permission to bake for you. So, the security of your funds is guaranteed by Tezos blockchain. (from FAQ)

So you don't need to bring coins to their accounts, you only delegate and your coins remains yours.
So no risk)