Looking for information to add a ui or pop up with rules of a server you must accept to proceed
You could make a client mod that uses the ConfirmationDialog BeamMP/lua/ge/extensions/MPCoreNetwork.lua at f98b22c186b7d1ba44195de7b6ebd28b5e077f66 · BeamMP/BeamMP · GitHub Extensions
Or wait for the dialog packet to be merged and published in the server prelease Implement Dialog packet and add MP.ConfirmationDialog by WiserTixx · Pull Request #427 · BeamMP/BeamMP-Server · GitHub
Or have a look at how other mods like neverless’ afk kick show a popup BeamMP-ServerScripts/AutoKick at main · OfficialLambdax/BeamMP-ServerScripts · GitHub