This is given in the chapter B07 of the FIDE Handbook and reads as follows:
5.1. All Head of Delegations/Captains/Trainers at official FIDE events like Olympiads, World, Continental and Regional Team Championship, are required to be a licensed trainer, and for World and Continental Junior, Youth, Cadet and Schools Championships, to be a licensed trainer or International Organizer, failing which, will need to apply for a captaincy license.
5.2. Only licensed trainers and holders of the International Organizer title, as applicable to the official FIDE event, or those with a captaincy license and Federation Officials given special permission, are allowed access to the official playing venue and playing area (as per the tournament regulations) and be entitled to free board & lodging (where offered by the organizers).
5.3. If a Federation is unable to organize for a licensed trainer or an International Organizer to fill a Head of Delegation/Captains/Trainers at the designed official FIDE event, TRG will issue a captaincy license provided the following conditions are met:
a) An application must be made together with a registration fee which will only be valid for that particular event.
b) Compulsory attendance in an orientation course to be jointly organized by TRG and the FIDE Events Commission.