Novice Tidal Question…

Let's start with "its just a streaming service, what you do with the stream is up to you".
I guess it comes into your bluesound node now?  You have therefore signed in and authorized that device.  to use another device you sign out and sign in elsewhere.  It's not clear to me how one signs out of Tidal on Bluesound.... and tidal *may* let you be logged in on two devices so long as you are not streaming on both simultaneously. I'm not 100% sure since my Tidal is pretty much signed into by my Roon ROCK 24/7.

Once signed in on your phone, pad or other similar device you can then use a protocol like airplay to send the stream to another device.  You could also use Bluetooth or USB.

Your Tidal subscription will recognize when you are using it now and will disable steaming on your home system using BluSound (much of the time). Although, I have noticed in the last several months when I leave the house with music still playing and proceed to play Tidal in my car; however, when I come home it is still playing on my the home stereo. Alternatively, you can change to a family plan sort of subscription that allows I think 3 devices using the account at the same time. Also, I recommend upgrading to a separate DAC. The internal DAC of the Node2 is mediocre. It’s streaming and app quality are very good though.

I download music from Tidal to my phone, then play it back in my truck - cell service around here is marginal, and I'd be using a ton of data  anyhow if I were trying to listen to material I hadn't downloaded.

My interpretation of a single user is 1 simultaneous stream at a time. I leave Tidal logged on at several devices and only ever use one at a time, never had a problem.