I don’t understand the question. The quote, without the accompanying context which I can’t find, just says the sign up without using a promo code or referrer. In which case, of course you won’t get any reward.
I’ve not seen any prohibition against putting your promo code on your main site. It often accompanies a DreamHost logo link that includes the referrer. But there is a warning that if someone signs up with your code and them breaks the ToS that you’ll be permanently dropped from the rewards program.
I don’t see what Google Ads has to do with this.