I have a few friends who attended SASTRA University. According to them, there are no such donation seats available. The admission process is completely based on merit. It is one of the few private universities that take admission through JEE Mains score. The counseling process is transparent and due to high competition, getting admission at the university can be tough. 

The only way to join SASTRA University without merit-based admission is through the NRI quota. However, the number of seats is limited. You will need to register for it. The fees will be different too.