From the author's README on Thunderstore

Nami Post-Timeskip — ReSkate cosmetic mod

Starter package for a Nami-inspired cosmetic project for ReSkate on PC.

This is a metadata/package-layout fix, not a finished in-game cosmetic. It does not contain a compiled .fbmod, model, or game-ready textures yet.

Included

manifest.json: package metadata
icon.png: placeholder icon
README.md: project information
BUILD_AND_INSTALL.md: build workflow

Install Nami Post Timeskip Cosmetic

You need ReSkate and your own copy of skate. on Steam.

Open ReSkateLauncher.exe and go to MODS.
Search for Nami Post Timeskip Cosmetic and click install. The launcher also installs anything it depends on.
Press PLAY. In game, the MODS tab of the ReSkate menu (Insert) turns it on and off.

Or install it by hand: download the .zip and drop it on the launcher window, or unzip it into its own folder in Mods\ beside Skate.exe.

Maps show up in the ReSkate menu's level list. To join a server running a custom map, you need the same map installed. If the game won't load after installing, see known issues.

skatemods doesn't host or review this mod. The download comes straight from Thunderstore. Only install mods you trust, because scripts can run code.