1. Click on dispute
2. Chose "My dispute isn't based on any of the reasons above. I would still like to dispute this Content ID claim." (because the first 3 options implicate that thit claim is correct)
3. Then chose "License: I have permission or a license to use the content claimed in my video."
4. Check "I have permission to use the content from the copyright owner."
5. In the text field "Please include your license information below (required)" i paste the text: "This is a f alse claim. The correct original song is: https://filmmusic.io/song/xxx" (Replace the link with the correct filmmusic song link)
5. Sign with your name
7. Send the dispute