Form With Multiple Uploads Doesn't Submit

I am having issues with a form that I am using for customers to upload their artwork for printing. When I test with one image between 5-10mbs it uploads and submits quickly and correctly. But, when I add more than one file over the 5mb size, the arrows just cycle and nothing is submitted. I should say, it isn’t the multiple file issue, I tested it with smaller files and it worked perfectly. Also, all the sizes have been set to 10mb in the form.

I don’t get any errors or pop-ups within the form, the processing arrows just go on forever.

This is for a new product and my customers are starting to get fussy, please help!

You can view the existing form at https://www.queencityprints.com/fine-art-giclee/order-form/

https://www.ads-software.com/extend/plugins/contact-form-7/