There is no doubt that Mbappe is a talented player. Mbappe has the ability to score a lot of goals. We haven't seen Mbappe play well in the first three games of the season. However, Mbappe managed to score two goals in the fourth match. Madrid won 2-0 against Real Betis and Mbappe scored both goals. Mbappe is slowly adapting himself to the Madrid players.
Mbappe shown his great talent since he was very young as a teenager in Monaco, and continued to show his world class ability in PSG through many years and more than that with his national team in many big tournaments. The transfer to Real Madrid is a first step to achieve his dream that includes many targets, playing for his favorite club Real Madrid, getting chances to win big titles. He is in a right place already but there are many challenge for him to go through and win titles. He needs to work friendly with the coach and his team mates, and should not show his high ego and disrespect his team mates as it is not good for his career in Real Madrid.
But Ancelotti's main challenge at the moment is trying to keep his squad's performance stable in the next few matches. Because right now several players in Madrid's squad are facing injuries. And we haven't seen so many important players of Madrid facing injuries at the same time in the last few years. And finding a suitable replacement is now the biggest challenge for Ancelotti. As many players are injured, Ancelotti is unable to apply any new formation or match strategy. Madrid will need a long time to find strong form again. In the next few weeks we will probably see some erratic performances from Madrid.
The bigger challenge for Ancelotti at this moment is dealing with many injured players that is not his expectation when the season began. He needs to manage the team going through this hard time with acceptable results and waiting for injured star players to come back.
I don't have doubt on ability of Ancelotti in tactics because he is a great and successful coach with long coach career in many big clubs, Juventus, AC Milan, Real Madrid, Chelsea, Bayern Munich and Real Madrid now. Having many injured players at the same time is always big trouble for any coach and sometimes a head coach can succeed to get good results but other times fail with bad results. I believe Ancelotti will help Real Madrid to exit this mini crisis successfully.