Thanks for your interest in joining the botnet!

I'd recommend using "password" as your password and "root" for the username. Attackers have a lot of stuff going on! Don't make their job all complicated, make it easy to remember.

Older operating systems like a really old Linux distro or Windows XP are the best, since their performance requirements are a lot lower, giving better overhead for the crypto miners that will be installed. Modern OSs waste resources on security features and such.