Darko is an icon pack. It is not a standalone app, you need a third party launcher to apply it.
Darko: A dark set with a shadow for depth. Use it with any dark wallpaper for a better effect of depth.
What is included:
♠ 3.500+ HD icons (256×256)
♦ 66+ matching HD cloud wallpapers!
♠ Launchers support: Action, Adw, AdwEX, Apex, Atom, Aviate, GO, Next, Nova, Smart, Solo …
♦ Icon hiding for non-themed icons
♠ Dynamic calendar (for Nova Launcher)
♦ Alternative icons to choose from
Added new icons
Fixed Android 11 issues