FreeBusy uses EWS (Exchange Web Services) protocol, not ActiveSync.
EWS is typically deployed together with OWA (Outlook Web App).
If your company offers OWA to employees, then you can use FreeBusy,
and you can sign up on your own without assistance from your IT department.

If your company has a custom Exchange deployment that doesn't offer OWA,
we can work with your IT department to create a dedicated solution.
Please contact us for more details.