You don't really need to say who,.
If you don't know about there being a contract, then you don't have one. You'd know if you did, because they are heavily negotiated for before you begin employment.
You are an "at will
" employee in your state. That means that you can legally be terminated without cause, without warning.
Now, some employers have imposed on themselves more strict requirements for termination
. It sounds like your employer has, as well. They have a requirement for warnings. Regardless, those requirements are internal to your company and the only requirements on whether or not the employer can terminate you for not signing up enough people in their program.
Legally, they absolutely can add that as a requirement of your employment and, if you fail to meet the arbitrary number they come up with (and I completely understand that the figures are not really thought out), they can terminate you, as long as they do so in accordance with their established termination policy.