The license is CC BY-NC (share by attribution and NON-commercial use only) and therefor identified by Creative Commons as "This is not a Free Culture license"
You kind of expect that from FB, right?
This is clearly better than "all rights reserved" but don't let it fool you into thinking this is what the general spirit of "open source" is about.
What is the true definition of "Open Source"? https://opensource.org/osd
'Fit Open' is people powered, outdoor fitness & endurance sports.