I’ve had no issues for a couple of reasons.
First, I read this two or three times http://admission.universityofcalifornia.edu/counselors/files/tag-matrix.pdf . I noticed some schools (like UCSB) have specific math and english timeline requirements.
Then I decided my top two TAG schools, and read everything on their website about the program and requirements at the specific campuses.
After deciding, I filled out this https://uctap.universityofcalifornia.edu/students/index.cfm and went through the steps.
Hope that helps!