Basically, there is a one moderator who isn't playing but instead leads the game, and they choose who is mafia, who is the cop and who is nurse, while everyone else is a citizen.
They will say "Night" and that's when they ask the Mafia to PM them who they'd want to kill. After that, the Mod will ask the Cop to PM them who they think is (part of) the Mafia. The mod will give them a yes or no, and if they guess right, they can subtly bring up the culprit during the "Day" Discussion while still protecting their identity as Cop.
After the Cop picks their guess, the Mod then asks the Nurse to choose someone to save. They are allowed to save themselves once.
After that, it's "Day", and depending on who the Mafia chose to kill and who the Nurse chose to save, there will be either a death or a save. If someone dies, they reveal their role and everyone goes on to discuss who the Mafia might be. This includes the Mafia who tries to divert attention from themselves.
You guys vote who you guys think is the Mafia, and then based on the votes, someone either dies or is saved. If you are voted against, you can choose to defend yourself but that doesn't really help lol. The dead person then reveals their role. This cycle repeats until the Citizens win (they killed off all the Mafia) or the Mafia win (they killed off the Cop and the Nurse).