Those who join US Army in MAVINI program will get in the position called PRIVATE.
Private is the lowest rank in US Army. It is 18th rank below the Second Lieutenant (Officer Level).
If you are already a US Citizen and have joined ROTC and have Undergraduate degree, you can join in Second Lieutenant.

One of my cousins joined in Private in MAVINI program. He says he is at the lowest rank.

Rank Reference:
https://www.military-ranks.org/army

May be he just had high school diploma while joining army. Ranks depends upon education, the highest you can go is specialist if you have bachelor degree through MAVNI.

He was in F1 status and completed associate degree in medical technology.

Then he can join as PFC, tell him to give his associate degree to s1 or his someone higher up to get ranked up.

Then he can join as PFC, tell him to give his associate degree to s1 or his someone higher up to get ranked up.