Maybe the original is an old song in the public domain and that's why the song went to the Grammy's instead of to court? Or maybe they asked permission?
http://www.thatsongsoundslike.com/2015/04/15/5-songs-that-sound-like-girl-crush/
Old School Love Divine Brown
https://youtu.be/Q3jA56A3Yy4
http://www.musicnotes.com/sheetmusic/mtd.asp?ppn=MN0128822
http://www.samethattune.com
http://www.musicnotes.com/sheetmusic/mtd.asp?ppn=MN0148163


http://www.onlinesheetmusic.com/girl-crush-p449294.aspx
http://www.musicnotes.com/images/productimages/large/mtd/MN0089665.gif