What are the requirements to join UTPA?

It depends on the particular program you wish to enroll. For undergraduate admissions, you require your highschool diploma (official HS transcrips), and the ACT (18) or SAT (860). If you graduated top ten of your HS class, you do not have minimum score requirements.
For Graduate School, you are required to have a good GPA and sometimes the GRE, but it depends on the program.
The official requirements are in UTPA.EDU/GradSchool