Sacrofano Train Station

No. There is a bus stop, but I don't know how frequent the buses are since they are mainly used by commuters. Be aware that the Sacrofano station is not in the actual town, which is up the hill at a distance from the station. Are you going to Sacrofano for a specific day trip or do you plan to stay there?

I've been told that I can take the metro from the Flaminio Rome Metro stop to Sacrofano. I have not verified that. Each Christmas vacation, I stay at Fraterna Domus, a convent in Rome. They have a large retreat center in Sacrofano where, this year, I will be travelling to but they warned me that I need a car. I am seeking an alternative.

I will be staying at the retreat center in Sacrofano for 4 nights. They made it clear that I would need a car. Again, I'm looking for an alternative.

It's not the metro that goes there. You will take the Metro A to the Metro A Flaminio station. There you walk to the Flaminio Train Station (a suburban line train station) where you take a train (a suburban train) to Sacrofano station.

The Fraterna Domus center in Sacrofano is actually only 2.5 km from the station (1.5 miles) therefore it would be a 30 something min walk, but if you have luggage that might be a problem. This is the walk path from the Sacrofano train station.
I don't know if the fraternity can arrange some private car service for you, as no buses go there. It looks like it's a suburban community, called Monte Caminetto, full of single family villas (actually looks like an upscale residential neighborhood similar to a typical American suburb).