I tweeted that question to the UFCPI but they never responded.
it open to people. ive seen people who are training partner of ufc fighters go there and get looked at. they also had other sports people there like the golden knights and boxers.
i dont think they let someone like fedor jsut show up and use it but there been bellator invicta fighters who are with ufcfighters be allowed to use the place or get looked at