I do not think there is actually any chance for Roma. First of all, they will have to win the match that they have left with a big goal difference. Secondly, Atalanta will have to lose both of the matches that they have left by a big goal difference in both of them. And I think all of those things are definitely not going to happen. Even if Roma is able to win the next match and Atalanta somehow manages to actually lose the two matches that they have left, I still think that Roma is going to be behind because of bad goal difference. I just do not believe that Atalanta will not be able to take even 1 win of the matches that they have left. And both of those matches are against mid-table opponents, Torino and Fiorentina.
Their chance for Roma will come from Europa League final match, not from Serie A matches.
If Atalanta win against Leverkusen, they will be appointed a spot to Champions League as a Europe League champion. Their spot in Serie A will be passed to Roma even Roma will finish this season at the sixth position.
It is more interesting about Serie A clubs if Fiorentina win the Conference League, they will be appointed a spot to Europa League and a club at the ninth position will be able to join Conference League.
This means, in summary, if both Atalanta and Fiorentina win Europa League and Conference League, Serie A will have 9 clubs in Europe tournaments next season.
How Italy can have nine teams in Europe next season