Let's do a little reality check here, I highly doubt you can buy traffic on Fiverr and have it convert on any ClickBank offer. Quality traffic is not acquired on Fiverr (that's for sure). Focus on building a value adding funnel like described in the post rather than looking for a shortcut. You can't just spend 5 bucks to make 40 in 5 minutes, I'd be a billionaire otherwise :).
Outbrain is not necessarily the network of choice, it was just an example. As for tracking the ROI usually you'll want to track campaigns in Google analytics and track clicks on affiliate links as event and average value/email or you'll want to duplicate the post and run paid traffic to the duplicate so you know exactly what the conversions are as you can put them in separate email lists etc too.
The General Data Protection Regulation (GDPR), which took effect on May 25, 2018, is a set of regulations governing the use of personal data across the EU. This is forcing some affiliates to obtain user data through opt-in consent (updated privacy policies and cookie notices), even if they are not located in the European Union. This new regulation should also remind you to follow FTC guidelines and clearly disclose that you receive affiliate commissions from your recommendations.
In the past, large affiliates were the mainstay, as catch-all coupon and media sites gave traffic to hundreds or thousands of advertisers. This is not so much the case anymore. With consumers using long-tail keywords and searching for very specific products and services, influencers can leverage their hyper-focused niche for affiliate marketing success. Influencers may not send advertisers huge amounts of traffic, but the audience they do send is credible, targeted, and has higher conversion rates.
The best way to think about affiliate marketing is quality over quantity. There are a lot of small websites that will promote your product, but the key is finding a small number of partners that will deliver conversions. For example, an equity management services firm has over 20,000 affiliates in its system, but only about 25 affiliates generate 85 percent of revenue.
When promoting affiliate offers, just make sure you are fully aware of all the terms and conditions attached to your affiliate program. Some programs can be strict about how they allow you to promote their products. For example, some may limit you to banner ads and links only, while others will allow you to use paid advertising, but won't allow email marketing.