It takes time for Mbappe to become an important player at Real Madrid and I am also sure that he will slowly adapt well with his teammates.
I also believe that Mbappe will be able to adapt to Real Madrid and will become one of the best strikers in the world. Right now I see that Vini and Mbappe still don't have a good bond. That's normal because both players are important players for Real Madrid right now. Both still have their own egos. It will take time but I don't think it will be long. Vini had a difficult time when he first played at Real Madrid and Mbappe will feel the same way.
There is no doubt that Mbappe is a talented player. But adapting to the new environment and new match strategy of La Liga is a bit difficult. Moreover, Mbappe's position at Real Madrid also had to be changed. Because of these reasons, Mbappe's performance is somewhat erratic. But Mbappe is very talented. He will surely adapt himself to this squad very quickly.
Mbappe and Vini do not have a friendly relationship. Moreover, Bellingham, one of Madrid's most important players, is not in the squad yet. Bellingham's return to the squad will surely stabilize Madrid's performance.