How are you inserting the Image?
Because what ever method you are using is creating a float:left setting for the image container with the rule
.paapi5-pa-ad-unit.pull-left {float: left;}
This make me think there must be a centered option.
If you cannot find the centered option, we can apply custom CSS to change it until their HTML changes….
The rules below in the theme Global Custom CSS Rule box should do that
.paapi5-pa-ad-unit.pull-left {float: none;}
.paapi5-pa-product-container {margin:0 auto;}