According to this source the word 'crony' is Cambridge university slang; Maybe is too geeky to call someone this way instead of a guy, fellow?
synonym: guy, fellow, bro etc.
Crony has changed its meaning over time: now its meaning is pretty sinister on both sides of the herring pond. I would advise against using it about a personal friend of yours.
The Cambridge Dictionary has this to say about it:
a friend, or a person who works for someone in authority, especially one who is willing to give and receive dishonest help
Meanwhile, if you look at Merriam-Webster, the definition seems quite innocuous:
a close friend especially of long standing
but look at the examples:
The mayor rewarded his cronies with high-paying jobs after he was elected.
the criminal's cronies were also closely questioned about the illegal gambling operation