Novice Tidal Question…

I’ve got a Tidal subscription which I enjoy quite a bit in conjunction with my Bluesound Node 2i.

Is my understanding correct that I can also use this Tidal subscription to listen in the car or stream from my iPhone to an Apple TV/Airport Express sourced system?

If so, how is this done?  I keep defaulting to an invitation to a trial subscription to Tidal when I try to use it outside the Node 2i.  (My grandkids de-bug most of these type issues for me but they’re all busy with summer vacation matters today. 😂)
you can use your Tidal subscription on multiple sources, just need to log in
Yep just put the Tidal app on your phone and log in with your account info.  Then either bluetooth to car radio of use Aux input (hardwire) .  I have to use the later as my car is 13 years old.
Sure can. You are just putting lossless through compression transmission. Not much difference from Spotify direct.   
Except for the monthly fee.
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.
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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. 
Thanks very much to all!

My problem turned out to be in the nature of having too many irons-in-the-fire….The earlier Tidal app on my iPhone was occupied somehow (Still not too proficient with this stuff.) by an old trial account that was abandoned before it got fully functional if that makes any sense.  I ditched that app and downloaded it again, this time being able to log in with the account particulars from the iteration of Tidal that my Node 2i is using.  Still some intermittent WiFi bugs to be addressed but it works very nicely in the car after a network reset with my cellular service.
Tidal plays perfectly in my car, but don't get too excited as it's doubtful anybody here's gonna ride around with me.
Tidal only allows one stream at a time. 

If you stream with your blue node and then try to stream on your tidal app it will not let you. 

BTW get a external DAC on your Node2 and you will be amazed. 
With good pair of headphones and Audioquest Dragonfly Cobalt or Red DAC your Tidal subscription could be mobile and you could enjoy high res sound anywhere… same type connection could also work for a car but only if the car equipped with 3.5 aux input. 
It is different than the BlueSound app. It is called tidal connect. Then you can stream your tidal music in the car or to your Sonos or BlueSound. It is less quality but better than a lot of other apps. It works great in my cars.