Google Scholar as well as similar platforms are far from being complete. They use a limited number of journals, databases and other platforms to collect entries automatically.
I will add something from my personal experience: posting papers on Academia.edu platform shortening the period for recognition of your paper by Google Scholar crawl...
Dear Rohit, you can add your article in Google scholar manually. Moreover, copy your research gate link and paste in your Google scholar homepage. Google scholar will pick up your article more quickly. Thanks