You were right and Barcelona drew with Atalanta, but Barcelona tried and played great, but Atalanta played one of their best games in a while and Ederson's goal was just great, real soccer art.
I think if Szczesny had played better and not missed the ball between his legs, Barcelona could have won, but they still helped Real not to go out, which means that at least there was no contractual game here and everyone played to their full potential.
Barcelona played without any burden in this match, because even if they get any result, their position is really safe to be in the last 16. Atalanta who had to accept the fact that they had to be in the play-off round after failing to get a win in this match. Yes, the draw they got only made them in 9th position, only one rank below the safe position to be in the last 16.
They worked hard, but their hard work was not enough to make them safe because the opponents they faced were also not that easy to beat.
Barcelona played with a strong enough squad and Flick decided not to act like Arne Slot, who actually removed his main squad for the match with PSV and in this case you can really say that they played without straining. Barcelona came out with Yamal, Rafinha, Lewandowski in the lineup and all the main defenders and goalkeeper also played Barcelona to win, just at the end was unlucky and Szczesny did not save, but otherwise did not play for a draw with Atalanta initially and did not try to spoil Real's reputation, lost to Atalanta, so that Real did not get into the 1\16 Champions League final.