In the simplest way to explain it; when you purchase a song for download, you are only paying for the personal right to own a copy of the recording, enjoy it, and listen to it. You do not OWN the musical arrangement or composition itself. This applies to both digital copies and physical album copies you would buy at a store.
In order to profit on someone else's work or ideas or use it in any public fashion, you have to license the use of the IP (intellectual property) from the owner or official representative of the owner of a copyright if their content is not open source, creative commons, or some other form of community license.
In the FiXT Store, the blue and red checkmarks next to the music simply indicates that the content is available to use with the free and monetized tiers of the FiXT YouTube Music Program. If you are creating non-monetized videos through our free plan, you must still follow all of the conditions of the program. If you are using the music for partner channels or monetizing videos, you must purchase a YouTube Music Subscription for the channel(s) you plan to use it on and follow all the additional conditions.
View all the rules & conditions at http://fixtstore.com/youtubemusicprogram