Under Basic account, is it available to get certificates for three free courses(Python, C++, Linux) if I would have completed them all? Or should I register paid account for them? Thanks in advance.
Yes, you can get free certificates for the free courses. The courses and their certificates are 100% free of monetary costs.
To earn the certificates, you need to complete and present the Real Robot Project for each course. This fun part that requires some effort and is not “free” in that sense 