Live access to Celtics game on Smart TV using Verizon FIOS

[Grayfam]

We are renting a local hall for a birthday party for my son and the hall has a HDTV that is not connected to cable, but it is a smart TV and it has an Apple TV connection.  We want to get the live Celtics game on the night of the party in January.   Does anyone know how I can access/livestream Verizon FIOS and the channel the Celtics will be on that night so we can watch it on the rented TV in the hall?  Thank you