First, if you are interested in graduate study in evolutionary psychology at PLEEP, you need to apply to the Department of Psychology in the College of Arts and Sciences at the University of Pennsylvania. Information about the application is located here.
Second, if you’re interested in evolutionary psychology, then PLEEP might be a good option for you. (You should also be sure you've looked at this page, for other options.) If you’re not, then probably your best bet is to look elsewhere. The lab is explicitly evolutionary/adaptationist in its focus.
Third, applicants are welcome from any discipline. If you have an undergraduate degree in biology, philosophy, political science, or other area, that’s just fine. You need not have a degree in psychology to apply.
Fourth, you may apply to work with either Robert Kurzban or Coren Apicella, as they both work closely together and jointly direct the PLEEP lab. In addition there are people in closely related areas here, including Robert Seyfarth, and Paul Rozin, and in the Psychology Department, Claudia Valeggia and Eduardo Fernandez-Duque in the Anthropology Department, and any number of other people spread across Biology, Wharton, Philosophy, and so on.
Finally, as you can imagine, the admissions process is complex, and no faculty member has complete control over it, and the process is very competitive. In addition, in the modern funding climate, while it’s true that Penn now guarantees five years of funding, you are very strongly encouraged to seek external funding.