SEO for a High DR Blog

Forgive me if this question seems kinda basic, but I'm accustomed to handling content strategy for smaller blogs. However, recently, I got a great opportunity to work with a company whose DR in Ahrefs is 80+. So, it's highly authoritative.

And yet, in terms of organic search, almost none of their blog content ranks and the main organic traffic comes from branded search terms. As I work out which keywords to target and start producing optimized content for them, do you have any advice on how to help them rank for more competitive keywords?