@bighorrorfanTTV
You need to own base GTA V in order to play FiveM, once you own GTA V, go here:
https://docs.fivem.net/docs/client-manual/installing-fivem/ - and follow the steps on that page which will take you through the FiveM installation.
Make sure you join the RPUK, Discord server in order to connect to the server here
https://discord.gg/roleplay - follow the steps in the discord to verify your Discord account.
Once you have installed FiveM correctly, make sure you have Discord and Steam running and search roleplay.co.uk in the server browser.
Regarding the application question, I am assuming you're reading the Police application, that is an in-character question related to your in-game's character storyline.