Hello @Danny,
Everything is working the same with the code we sent but you didn’t configure YITH settings correctly and had Show add to quote option with value “Product in the Exclusion List only” and mostly your products in the list are out of stock ( https://prnt.sc/YyqRUndfh52s ) but you should have -> https://prnt.sc/SIJrh0ai7I2G to show Request quote for all products that are in stock.
Regards