Looping Through Categories of a CPT

I am trying to create tabs using the Foundations framework, outputting posts from a custom post type called testimonial and filtering them through their assigned custom category called filed-under. What am I doing wrong in my loop?

What I Have Working

What is Not Working

Link to Demo
http://staging-newmummycompanyca.temp312.kinsta.cloud/testimonials/

Code

CODE V2