Tips for getting through career site applications

Hey guys,

I have been applying for product roles through linkedin easy apply as well as company career sites. I have got mostly rejections , even though i have a pretty good experience from MNCs and a degree from Tier-1 college (IIT). What could be the reason ?

Questions:

1. What could be the reasons for rejections ? Are these always ATS rejecting it ? If so, pls suggest some working methods to make my resume ATS friendly
2. What other method worked for you guys in your application process ?