The colors look washed out. Fix: You likely downloaded an HDR file but played it on an SDR monitor. Ensure your TV supports HDR10. Alternatively, use software like VLC or MPV to tonemap HDR to SDR (though it won't look perfect).
The only way to get a legally is via Digital Copies included with the physical disc or through "Download to Own" services that offer high-bitrate MKV/MP4 files. Interstellar 4k Dolby Atmos Download