Featured Image Issue

This is the site I’m working on:
https://www.karensgotmail.com/

This plugin looks to be exactly what I’m looking for, but the featured image doesn’t crop itself into a 150×150 thumbnail. The set width option doesn’t work for me since all of the images my client has uploaded are different sizes and the auto option doesn’t work because of the same reason.

Is there a way to fix this?

https://www.ads-software.com/plugins/easy-custom-auto-excerpt/