If you already own the game but can’t update due to a banned or offline Switch, consider dumping your own update from a friend’s console or updating via local wireless — not random .rar files from the internet.

It looks like you're referencing a file name for a Nintendo Switch release:

Major additions included in the Update 2.0.0 ecosystem include:

Adjustments to character stats and enemy difficulty curves for a fairer challenge.

: Enhanced UI elements, faster loading times, and bug fixes to resolve issues reported in previous versions. Performance Optimization

He downloaded the .rar. No password. Inside: a single file, Abathor_v2.0.0.nsp , and a readme named DO_NOT_RUN.txt .

Tailored for seasoned players, featuring more accessible save points.

This update is for all legitimate owners of Abathor.

Originally released for PC and consoles, Abathor gained a cult following for its old-school challenge. On Nintendo Switch, the game ships as a digital title (eShop) with periodic updates improving performance, balance, and content.