There are 3 softball fields and 1 baseball field at this facility. This is actually part of the Mission College which is a community college in Santa Clara. Parking Lot D is the closest parking lot to access the fields.
There is a $3 fee to park your vehicle all days of the week (weekends included). Here is a pic of the parking permit machine where you can get your ticket to place in your vehicles. Looks like both cash and cards work.
A close-up view is below.
Beware that there is campus parking police regularly driving by to ticket the cars without permits.
There is also a $5 entry fee to enter into the fields. No ice chests are allowed since they have a snack shack and they would like you to purchase food and drinks from there. You may want to bring extra plastic bags to get ice just in case your players get hurt and need ice. There are not equipped with bags to dispense ice when needed.
Here is a pic of the snack shack and their menu.
As in the other places that charge an entry fee, there are real restrooms to use instead of port-a-potty.