Apply it in your launcher

Applying the pack is done in your launcher's settings, and the wording varies by launcher. In every case you are looking for an "icon pack," "icons," or "theme" option, then choosing Zenith Icon Pack from the list of installed packs.

• Launchers that support icon packs — for example Nova, Lawnchair, Smart Launcher, and Niagara — expose an icon-pack (or "icons"/"theme") setting. Open it, pick "Zenith Icon Pack," and confirm. The home screen redraws with the Zenith icons.
• Zenith Launcher recognises official Zenith packs first-class and lists them ahead of others in its icon picker. Apply it there the same way — through the launcher's icon setting. See Zenith Launcher's personalization page for that launcher's exact controls.
• Stock Pixel and Samsung launchers do not support icon packs at all. No setting exists there to apply this or any pack; you would need an icon-pack-aware launcher first. This is a limitation of those launchers, not of the pack.

Two independent scopes are worth knowing. Choosing the pack as your launcher's default icon pack themes every app at once. Separately, most icon-pack-aware launchers also let you set one icon on one app by hand — see assigning a single icon.

See also. What's inside the pack · Troubleshooting