An important part of building authority is managing your site structure to make optimal use of the authority that your site earns through incoming links. In the SEO world this is often referred to as technical SEO, since it involves some of the more technical code work done in SEO.
A colleague of mine often referred to this as “SEO Black Magic” because it’s the part where you do things invisible to users that can, in certain situations, give magical-seeming improvements to rankings (this is rare).
Ultimately your authority is going to come from other sites linking to yours, and the way you do that looks a lot more like traditional marketing. The point of on-site authority work is to ensure that you get the most benefit out of every incoming link. A poorly optimized site bleeds authority, essentially throwing it out the window rather than taking advantage of it to boost rankings.
A well optimized site makes the very most out of every drop of link juice coming in.