So is it a must to play the first game, like are the saves portable or do the decision in the first matter in the second or I can play coral without playing follower and watching the intro?
No, it's not a must play. The intro in NCC tells you basically what happened in chapter 1. (Saves are not portable, totally different game)
Having said that. I would recommend playing it. Some of the characters in NCC can be severely misunderstood if you don't play Follower. The biggest of these are Irene, but also Kirsten. Other characters from Follower is Maud, Rebecca, Andrea, Michelle, David etc. but their characters do not change due to things happening in Follower.
Things happening in Follower, however have a profound impact on Irene and Kirsten. If you decide to play it, I recommend the Renpy port.