These are typically installed directly to the Switch’s internal storage or SD card.
The "update link" refers to the —typically labeled UPD v1.0.1 or similar. Without the update, the base game can be unstable, and you will not have the final winter transfer window data.
The for Nintendo Switch is widely reviewed as a disappointing release that is essentially a roster update . While it remains a functional football game, it lacks the core features and engine upgrades found on other platforms. Key Review Takeaways FIFA 20 Legacy Edition (Switch) Review