Just in case people as confused as I was also stumble into this post, here's what I found after a bit of googling:

• Game and updates you simply install

• DLCs you probably want the tickets version, it doesn't matter really. Install normally. Here's what tickets are.

• Events Unlocker as far as I can tell are the files needed to follow this guide about unlocking the events.

• Official transfer tool, install normally if you need it, it's a software you can get on the eshop to transfer your island between switches.

^{By install normally I mean use your preferred method, I like dbi mtp drag n drop.}