Is Coursera a scam? Every damn time I select a course or skill to learn for free & with certificates it directly takes me to the fees for certificates! Is it okay if I learn new skills & courses and dont have a certificate?

Yes, it's ok to not have certificates and get knowledge from such free courses. Because at the end during interview they will test your knowledge,approach and not how many certificates you have.

I realised this after finishing my engineering and i don't regret it because at least I realised.

Never fall in the trap of collecting certificates & having zero knowledge.