You will get paid if they send you somewhere on orders, but if AROTC is like AFROTC it is a different pay scale. Per diem.
Otherwise, if you are sitting at home from May 15th to Aug 15th (summer break) do not expect any pay placed into your bank account.
It is only the summer between junior and senior yr that you will get paid to hang out at home.
I do not know regarding AROTC, but AFROTC states in their fine print how the pay schedule works. IE you must pass the PFA. You must keep a min gpa. You must this and that. It will also state that an MSI receives x dollars, MSII y dollars, MSIII z dollars, and MSIV A dollars per mo.