If you cannot find your song on Instagram Reels, you can search their system by providing your ISRC or writing out the song name and artist name (ex: Song Name Artist). If your artist is brand new, it may take some additional time for Meta to optimize the searchability of the content.
If your song still does not show, it may need to be redelivered to Meta (Facebook/Instagram). This may be the case if you have a waterfall release-type strategy for your tracks. Please reach out to us here if you need your content redelivered to this partner.
Additionally, Facebook/Instagram may not be available in your territory.
For additional FAQs, please check out this article.