You get to choose either a Republican or Democrat ballot.
Be sure to vote for the delegates who are pledged to your candidate of choice!
AND be sure to check the back side of your ballot to vote for any alternate delegates who are pledged to your candidate of choice.
It seems like some states deliberately complicate things so as to confuse people.
Yes, some ballots in some states can be very confusing! I posted what my friend in ILL told me as she was afraid that many ILL voters might not know about voting for the delegates and alternate delegates pledged to their candidate of choice.