You cannot play Roblox natively on Nintendo Switch
Roblox is not available as an official Nintendo Switch app
Do not download any “Roblox for Switch” claims from unofficial sources
If you want to play Roblox, use a supported device such as:
Windows PC
Mac
iPhone
iPad
Android phone
Android tablet
Xbox console
To play on a supported device:
Create or sign in to a Roblox account
Install the Roblox app from the official app store or website
Open Roblox and choose a game to play
If you only have a Switch, use it for Switch games instead of Roblox
Check official Roblox and Nintendo announcements for any future support updates