If any college gets from 15% all India quota and not take admission, can I be eligible for get MBBS admission through 85% state quota?

Yeah you are eligible for state counselling.

AIQ is done by MCC

State counselling is done by State Government.

Both are two different counsellings. If you want a college from state counselling then don't report for college allotted by All India counselling and vice versa.

All the best

Deekshitha Duggireddy, Student at All India Institute of Medical Sciences, Mangalagiri (2020-present)

Source: Quora Digest