Rashford can't afford to be lazy if he wants to become a key player in the Barcelona squad, and he must also be able to work with the existing players in the squad. If he continues to show his ego during any match, he may not get more minutes in the Barcelona team and won't be signed permanently by Barcelona after his loan period ends. I also want to see how Rashford adapts to the other players at Barcelona, as they were generally good players, judging by their performances last season.
Rashford now has a very strong responsibility because he has to prove to them, going to a new club comes with a lot of expectations, and being signed under Barcelona is a good one and a way forward. And another thing is, why did Manchester United decide to sell him? This is something that I don't understand because by now people need to understand that they need Rashford, and they are selling him of and since that is there wish then they should not be complaining even if they fail this season, and Rashford seems to be happier to be in Barcelona, and Barcelona is lucky to also have Rashford in Barcelona.
It won't be that easy for him to join Barcelona because he has to adapt to a new, different pattern and players, so it might take a little more training for some adjustment. It will take a little while, but Barcelona is cooking, and they don't want to disappoint. Despite their challenges with money, they are doing everything they can to top. And Madrid is becoming very unserious; even without any serious challenges, a lot is not going well, which needs to be fixed.