Earlier quoted context omitted.
Thank you for a link to a readable version of the agreement! It looks to me like "Permitted Users" includes "contractors" like those in a compensated research panel, and thus the Facebook/Google uses are plausibly enabled under the program.
Teenagers being paid with gift cards are absolutely not plausibly considered "contractors".
And technically, entering a contract doesn't even require a signature – just a "meeting of the minds" to exchange considerations of value, like "my data" or "cash value gift cards". (And, these programs may have included actual signed agreements – I haven't seen strong reporting either way on that.)