Is your brother not a member of the local chasse? If he is, then it’s considerably easier if you get him to sort it out for you. As others have said, you need to get a permit, I think a 9 day permit is about 70 euro. Members of the chasse can then sign in a guest for a number of days hunting....you’ll get a day ticket from the head of that local chasse, at which point you’re pretty much sorted.....don’t be overly alarmed if you start to question their general approach to hunting, in particular safe backstops, firearms handling etc....it can be a bit of an eye opener especially in the more rural areas....that said hunting in France is very, very well regulated....don’t think for a minute you can simply rock up, shoot what you want and bugger off.....it doesn’t work like that....each boar needs to be tagged when shot, then a fee Is paid to the regional chasse per beast unless it’s under a certain weight (most tend to be about 1kg under that weight!!), the fee goes towards compensating farmers for the damage they cause. In rural France the Chasse are like the NRA....they pretty much have free run over all land, I could be wrong but unless a farmers got many 1000’s of acres I don’t believe they can refuse the Chasse access....if they do, they’ve no longer got any friends!
oh.....and to add, in rural France no body speaks a word of English....that includes the local Chasse offices!......although down in the Creuse, the local Chasse that I go out with though my Helion was voodoo witch craft!