In the widgets parameters you have the “Post type(s)” option. Simply fill your desired posts type(s).
Please note that this request is related with the configuration of a third party plugin (WordPress Popular Posts), not with the use of your theme. As theme authors, the installation, setting or debugging of third party plugins isn’t part of the support we will provide.
If you want to go further or if you have more issues with this plugin, we advise you to reach the plugin author, he’ll be in a better position to answer you and help you.