CLion bundles a few native components built for Linux, these binaries won't work on FreeBSD. Noticeable examples are:

JRE (you need to install it in order to launch CLion),

fsnotifier (you will be warned on startup that file sync may be slow),

libpty (required for running apps with controlling TTY),

CMake,

and GDB.

So to start at FreeBSD you need to: