Ah, oops, I didn’t actually check the KB link, it went to a different article than I thought it did. The article I thought it linked to is this one:
Cloudflare is a company. iFastNet, who builds the free hosting platform, is a company. InfinityFree, which provides the client area, is a company. And then there are the various SSL providers, which are also companies (or at least organizations, Let’s Encrypt is not a company).
My recommendation is going for the Full SSL route with a self signed certificate, which I linked just before.
Flexible SSL is also a valid option, and so is going for the free SSL along with “Full (strict)” mode. You can go any of those routes too, they are not wrong.