Version 6.2.8 is an older iteration of the pack. Since then, the developer has introduced several major improvements:

How to Use Adaptive Icon Packs on Nova Launcher - One4Studio

The Nebula Icon Pack is not a standalone app and requires a to function on most Android devices.

: Recent versions (8.1.7 and later) introduced a premium icon request system, allowing users to prioritize specific apps for theming.