Letting Amazon customers know about my Free Shipping terms (FBM, Pro account)

Hi guys, a new fbm seller here, I have a professional account. I managed to set up my free shipping terms using a shipping template and everything works as intended except….my potential customers do not know that I am offering a free shipping over certain amount. I can’t include a sentence about my Free shipping offer in the title, or bullet points, I am not sure about product description, may be I can? I don’t want to violate Amazon’s policy. Anyway, my question is how my customers supposed to learn about my Free shipping if I am not allowed to announce it and Amazon does not say about it anywhere on the page, the only option is to add more items at the Checkout – I am not sure customers would be doing that trying to figure out how many more items to add to get the shipping free. I would be most grateful if you could share your thoughts on this please. Fbm sellers, how do you inform your potential customers about your free shipping offer? Or may be one can ask Amazon to do it? Thank you