Adwords coupon of 75 usd works if you have spent 25 usd. So you have to spend 25 usd x every coupon.
Adwords do not tolerate affiliate links anymore since a lot of time, you have to cloackin them or BETTER to direct the traffic to an opt-in page, in order to build a mail list,
then to Thank You page, the page they see after opted in, where they can see the clickbank's offer.
If you want a coupon without spendin any money, it's better referring it to Bing Ads.