Extract the file named "Avatar_RDA_1.0.pak" stored in the ZIP, and drop it inside Starbound's "mods" folder. That's all, now you can open the game.

How to find Starbound's "mods" folder:

- If you installed Starbound through Steam, open Steam, go to your game library, right-click Starbound, click "Manage", click "Browse local files".
Now you should be in Starbound's directory, and you should see the folder "mods". Drag the "Avatar_RDA_1.0.pak" inside "mods", and done.

- If you installed Starbound through GOG Galaxy, find the GOG directory, enter the folder "Games", enter the folder "Starbound", and you should see the "mods" folder.
Drag the "Avatar_RDA_1.0.pak" inside "mods", and done.