You can find .srt files for this specific release on the following platforms:
: A reliable source with multiple language options for Avengers Grimm (2015). Look for uploads that mention "WEB-DL" or "ETRG" in the title for the best sync. subtitle Avengers Grimm 2015 720p WEB DL x264 ETRG
the movie in a player like VLC Media Player or MPC-HC; it should detect and load the subtitles automatically. Official Streaming with Subtitles You can find