Try to find directory containing the FreeSurfer installation, based on environment variables and *educated guessing*.
find.freesurferhome(mustWork = FALSE)
named list with the following entries: "found": logical, whether it was found. "found_at": Only set if found=TRUE, the path to the FreeSurfer installation directory (including the directory itself). See 'mustWork' for important information.
logical. Whether the function should with an error stop if the directory cannot be found. If this is TRUE, the return value will be only the 'found_at' entry of the list (i.e., only the path of the FreeSurfer installation dir).
fs.home