SO to put a player model in Xonotic you should generally speak to the admins who run a server in your area. Then they put the model on the server, and people who can connect can see the desired model in game, since models are freshly download
Please bear in mind that since you have chosen a half human half blue cat with giant tits, you may actually have some trouble convincing the server admins to put the Krystal model on their particular server, but mate if that's your thing I totally respect that. I guess the challenge herein is to find enough like minded people to actually make a proper furry server, but hey its the internet, and that's why we make this game free and open, so you can take it and customize it.
I know there's some wild furries in openarena, you should probably check that out too.
Good luck and welcome!