Flycast Dojo can be retrieved from GitHub, or as a part of the Fightcade matchmaking service. However you obtain it, you will always have the option to use it standalone for P2P games using Match Codes over an internet matchmaking server, through a direct IP connection, or a virtual LAN like ZeroTier or Radmin.
For quick start guides, frequently asked questions, online replays, and community links where you can find people to play against, head to the Flycast Dojo site.
For general emulator help and updates on Flycast Dojo, check out the #netplay room of the Flycast Discord.
For Fightcade-specific help, be sure to read the pins and ask questions in the #flycast-emulator channel on the Fightcade Discord