Which Discord server did you get these messages from?
The original thread seems somewhat shady, considering that I couldn't find anything on the official Mercatox site regarding a giveaway.
The unofficial site also has this to say:
To activate your account and start transacting, you should to deposit funds to your new account, deposit must be not bellow 0.02 BTC or 1 ETH... Result: now you have balance on your exchange account that can be changed to other cryptocurrencies.
"bellow"
Definitely a scam. But I don't have anything concrete on the thread creator.