Open the Blocks tab.
Under Your Apps, tap a list to open Apple's app picker. This is Apple's own interface, which is why it looks different from the rest of Aura.
Select individual apps, or whole categories like Social. Picking a category catches apps you install later, which is useful if you tend to try new ones.
Tap done, and the Blocking Now section at the top confirms it's applied.
Start small. Two or three apps you genuinely lose time to beats blocking forty and turning the whole thing off by Wednesday.