You didn’t do anything wrong. The guy sounds like a douchebag. If he is “looking for a relationship”, maybe he should first get to know you and be a little open and vulnerable before he makes a statement like that.
By saying “I am looking for a relationship”, he is appealing to women’s heartstrings, which is shitty thing to do to start off with.
If interested in you – he should man up, tell you that he is attracted to you, enjoys talking to you, give you his details first, and be a little vulnerable to you to show he is serious.
The part “reply soon” sounds like he just fucking creepy. What does he want your ATM pin number next? Sounds like a scam artist. He probably has a Nigerian Prince friend too.
Fuck him. Move on. Trust your gut. Never give out your personal details until he has and you can confirm it. Have leverage if you need it.
Always protect yourself and keep that in mind before you let the dopamine take control of your brain.