Latest update 1618 Or version after
Go to http://steamcommunity.com/dev/apikey and in Domain name you put what you want then copy the key and then go to your server.cfg and put this:
# Steam Web API key, if you want to use Steam authentication (https://steamcommunity.com/dev/apikey)
# -> replace "" with the key
set steam_webApiKey "KEYS"
Replace KEYS with your keys
Well leave the " before and after the key
At the end restart your server is everything should work
This has nothing to do with Steam API stuff and has everything to do with this vRP resource. TriggerRemoteEvent is not a built-in routine (nor was it ever!) so this has to be defined by said resource.