Because they said i have 3.65 BTC there, but i must put some (little) cash to reach it....
Any service asking you make a deposit to be able to make a withdrawal is 99.99% scam.
I might probably believe it if they ask for Identification but I'll also doubt it even if they ask for identification.
Why should you believe them if they ask for identification?
If they ask you to verify your identity, it would even increase the risk of using their service. There's a big probability that they abuse your documents or sell them.
If the OP has never dealt with this site, then, he should know that this is a typical scam tactic.
There's no doubt they are just looking for some naive users that will fall to their bait.
I checked the trustpilot, no reviews or feedback. We have seen this scamming technique countless times.
If he deposits any amount, he will not get it back. So better not entertain these scammers.