Updated Thumbnail Support?

I searched the wiki and then the support forums and found an old discussion about this:
https://wordpress.org/support/topic/plugin-custom-content-type-manager-thumbnail-support?replies=16

I tried to follow the instructions but the interface has changed in the last three years. Would you mind sharing an updated way to add default assigned thumbnails(featured image) display in the custom post type page?

Thanks,

L

https://wordpress.org/plugins/custom-content-type-manager/