How to correct camera's position for 2D Sidescroller with Blueprints

Hi,

I’m studying the 2D Sidescroller with Blueprints video tutorial, and when I play the level, the camera’s position is wrong, and can’t show directly to the background. I didn’t find the tutorial mentioned this, so how to correct the camera position?

the screenshot of playing level is like this:

and the tutorial link is here:

Thank you