The scheme is actually very simple. These are fake (non-existent) crypto exchanges. There is no $20,000, there is no problem with his country's laws, its all a lie.
Here is how it works: You register on their fake website, "puwiriu.com" (By the way, there are probably dozens or hundreds of clone sites with the exact same content just on different domain names.). Then, they will pressure you to "deposit" some real crypto to "verify your account" or pay some bogus "withdrawal fee." Once you send them your money, its gone. Poof. Disappeared into the scammer's pockets.
Sometimes, they will even try to scam you for more money later on. Its easier to fool someone whos already been fooled once. But eventually, they will just disappear and move on to a new victim.