Add file upload in checkout

Hi!

I’m trying to add a option for ‘file upload’ on the checkout on my theme. I simply need to allow customers to upload their logo before making a purchase. (For printing on products)

Anyone knows how I can fix this?

I use the Flatmarket theme: https://themeforest.net/item/flatmarket-multipurpose-woocommerce-theme-rtl/9185162

Thanks alot for any help!