agree with post above- just see this as I was typing so I'll just post the details below in case they may help. I think your question applies to AFROTC/ NROTC/AROTC.
The DODMERB physical- you will have to take and pass for the scholarship to be official. Until then the scholarship offer is contingent on passing that physical. They will send you detailed instructions if you receive an offer for any branch.
On the PT, well, 2 answers, No, you won't have to complete another physical test in HS before you arrive at university. but please be clear that your scholarship if awarded is also contingent/ will not be activated until you demonstrate that you can meet the physical standards. This test is often given in the first hours/ days of arrival at school. You will line up and complete the run, pushups, crunches and pullups where applicable to those marine, navy, air force, or army standards -there you can demonstrate you meet these standards.
For NROTC people asked - well doesn't it count that I passed while at NSI this Summer - do I still have to pass at school? While in ROTC you will have to demonstrate that you pass the physical standards - there to my knowledge is no "off" and it's not like a driver's license you can hold up and say " PT Test? thanks, Sir, but I don't need to as I already have it". Those who don't pass, which happens most often due to form, scramble to shore up any gaps.
Hope this helps.