If you receive a scholarship through ROTC it will cover either your tuition or room and board. The scholarship will not cover flight fees or civilian flight training.
If you are interested in Army Aviation through ROTC then your best bet is to work hard in school, have a good GPA, a great APFT and test scores and do well in ROTC and try and be ranked high in your battalion. If you complete ROTC in the top 10% of the Active Duty National OML then you are guaranteed your choice of branches such as Aviation. If you are not in the top 10% then you compete with the remaining cadets for your branch selection.
There is no need to have any flight experience to branch Aviation through ROTC, in fact civilian flight experience will not be a factor in branch selection.
There is another option, you could skip ROTC, and apply for the Army WOFT program and enter the Army as a Warrant Officer and attend Flight School. You can apply as a civilian without a college degree but a degree would help make you more competitive. This would be the only process where civilian flight experience would be an advantage.