Yes, it refers to being one of the top 100 delegates by voting power, regardless of whether you are active or inactive. You can view an updated list of the top 100 delegates here.
Build a solid reputation as a delegate by actively participating in governance, which includes voting regularly, attending governance calls, and highlighting your unique contributions. Alternatively, you could simply acquire enough tokens to place yourself among the top 100 delegates; after all, this system fundamentally operates as a plutocracy.
The default filter in Agora is actually set to “Weighted Random.” In fact, I’ve observed delegates appearing in the list with as few as 100 OP delegated to them.