SEO & Ads for Software Store shopping cart

I’m finalising a compact, five-page PHP/HTML shop that sells downloadable software. The site is built for user reviews, subscription plans and free demo versions, so now I need to make sure the right buyers actually find it... (Budget: ₹600 - ₹1500 INR, Jobs: Content Marketing, Digital Marketing, Google Ads, Google Adwords, Instagram Marketing, Internet Marketing, Keyword Research, SEO, Social Media Marketing, Website Optimization)