First Read about Reddit before used it. Reddit makes the collections of subreddits because it supports the more informative community with higher active peoples according to fields. You can search subreddit according to your relevant category and posts your unique and informative content there. On Reddit Unique Content more beneficial of your channels or business.
If the post in Reddit is interesting in itself and is useful for users, then they will raise it. However, even if your helpful answer is at the very bottom, it is very difficult to push upwards.
There are few smmpanels which offers reddit upvotes. It's worth to pay, if you are having a quality content because it might work snowball, few fast ones, will push you to the trending one.
Paying for upvotes is unethical. An affiliate program such as yours suggesting such a thing doesn't bode well.
Their new ads platform is live. You can sign up and create promoted posts at https://www.reddit.com/adsregister I've tested it a small amount, unforunately many of the smaller niche subreddits that I wanted to target weren't available yet.
Well, he didn't ask about ethical things to promote it, just showed him an answer which wasn't mentioned earlier, that's all.