Is there still a shuttle at Avignon TGV station to the town center?
We are not picking up a rental car and need to get to center of Avignon.

"Avignon TGV station is located 2 miles from the city centre. Shuttle bus services run just outside the station and will get you into the city centre within 10 minutes."

http://uk.voyages-sncf.com/en/destin.../train-station

I was in Avignon earlier this month and I am not sure there is a shuttle anymore.
There is a train that runs between the two stations quite frequently.

The shuttle stopped in front of the post office, across from the city station so, shuttle or train, they'll get to approximately the same place. I used the shuttle but a while back, so figured the SNCF site was safer. But either way, there's a way.

The Avignon tourism authority says the shuttle train takes four minutes and costs 1.5 euros. This tourism operation is very useful for all sorts of things in and around the city
http://www.avignon-tourisme.com/home-1-2.html

Even if there weren't, it's not that far, one could easily get a taxi.

buy your ticket to Avignon-Centre and you will not have to buy a separate ticket upon arrival.

I was going to say taxi - it's a very short trip.

Having been through Avignon TGV station in May this year, it's worth mentioning I think that the trains don't stop there long, so it's a good idea to work out where your carriage is going to be and making sure you're in the right place on the platform as the large no of people and their luggage make moving round the carriages quite difficult.

you may also face the problem that we did which was other people sitting in our seats. You then have to decide - do you sit in the wrong seat and run the risk that its "owner" will turn up later and turf you out, or do you try to get the interlopers out of your seat? not to mention trying to find space for your luggage.

Good luck!