There is no fob or card; that’s what makes it nice and convenient. Payment is done directly through the Plugshare app on your phone. You have to browse to a specific station on the map, and then for that station, if it is enabled for “Pay with Plugshare”, there will be a space to enter the station ID number and your credit card number.
There was a bug for a little while that if you had location services turned off, or it couldn’t detect that you were within some number of feet of that charger, it wouldn’t offer the payment option, but I think they fixed that now.