Not sure what you are trying to do. But you can not SSH into the container.
That is just not supported or enabled, nor will it ever. That is not how containers work or should work.
It might be a special Azure feature, but i have no clue how that works.
Azure Web App / Azure App Service (or however they call it today) is a really convoluted service, always adding complexity where there isn’t any real need. Docs are also really bad, as they’re updated long after changes - even major and breaking ones.
Putting my rants aside, SSH won’t work if you’re using the official Vaultwarden image without any customization, as the server isn’t installed by default, and you will also need to set it up as per requirements.
Before losing any actual data, you may also like to read about the persistent storage and set up your .env accordingly.
Once you have everything ready, here¹ you can take a look at how you are supposed to connect using SSH.
¹ http#REMOVE THIS#s://learn.microsoft.com/en-us/azure/app-service/configure-linux-open-ssh-session?pivots=container-linux
(sorry for the way I’m writing this, but it looks like new users can’t post more than 2 links).