Act-Age is a really rough story as it stands. Looking purely at story, the reason why the president didn't select the MC was too weak. It was literally forced drama to drop the MC the first time and then bring her back again so that she can wow the casting directors. The MC herself also lacks characterization. I understand where she stands but I don't feel any sort of emotional connection yet.
The biggest thing that will hold Act-Age back is the art. The artist seems like they have difficulty drawing anything other than a front view of the characters. The 3/4th shots and profiles are awkwardly done. The paneling is also awkward. There also seems to be a lack of depth in the shots as well. The most important thing lacking however are the expressions. In the beginning, when asked to "show sadness", I understand that she's in a "deeper" state than the superficial acting of the other candidates but the eyes are lacking in expression. The same in the final test. The MC's expression doesn't look as severe as its implied to be when looking at a hungry wild dog ready to attack her. The double spread with the "fight scene" is also weirdly done. I didn't really understand what was going on. The lack of backgrounds is also a negative. There is too much white space and it distracts from the scene.
To put it harshly, it looks like an average to above average pixiv manga. The colour pages are well done but the actual art itself needs improvement. The artist's age might actually be holding them back here. The manga can succeed but the artist needs to improve in drawing expressions, especially for an acting manga.