When doing research on improving SEO/site traffic, something that was often mentioned was using Kindle Direct Publishing as a method for generating this.
Is it possible to upload resources that we have created and have them up there for free?
It is possible, though there are certain conditions.
If you publish with KDP and sign up for Kindle Unlimited, it will allow you to make the title free for a limited time (it used to be 2 days out of every 60).
You can upload ebooks to Smashwords, which will you can choose to give a free price tag for. Then, SW will redistribute the same ebook to all the major ebook stores. So For BN, Apple, Kobo, etc, you can make the price free.
Amazon.com claims it will do price-matching. If you report that a title is free on another ebook site, Amazon is supposed to match the free price. But what usually happens is that Amazon is price it free for a while, and then it will revert back to the previous price.
I don't know what you're trying to do from a SEO perspective. Amazon.com usually will capture the top spot for all book titles, but that isn't that good of a thing. If anything, it takes away SEO juice from your own site.