Error 404 – possible permalink issue?

I work for a steel fabrication company and we have a section on our website where customers can order various steel material. After the customer selects the material, inputs the sizes and clicks “Add to Cart”, the “View Your RFQ Cart” appears at the top, after clicking that link, it takes you to another page which then the ERROR 404 appears. Before, it would take you to the shopping cart after clicking on the “View Your RFQ Cart”.

How do I fix this? OR, how to I remove that “View Your RFQ Cart” link and ADD a button below my “Add to Cart” so that the customer can click on the button below the “Add to Cart”?

I have googled this same issue and it appears to be a Permalink issue, however, I’ve tried playing around with settings by doing what others have done to solve this issue and my 404 Error is still there.

My background isn’t in web design, so any help is very appreciative and pics are a plus!

The link below is to our companies website. You’ll see what I’m talking about. Not sure how to attach pictures here.

https://www.aisteel.us/product/tube-steel-hss/

Thanks