Can't see Chromecase in my list of devices on my tablet

[BSLMarketing]

Hi, pretty much as the subject mentions. In the app I tap on the devices button next to the queue button but can't see Chromecast.

Note I've gone through the instructions here 

"Google Cast lets you play or “cast” Spotify from your phone, tablet, or web browser"

and that the Spotify app and tablet are most definitely on the same WiFi network as my Chromecast.

[BSLMarketing]

Any ideas please??

I am really trying here and it's super frustrating because clearly the instructions aren't working. So either I'm mis-reading them or they are wrong! Following the instructions...

Listen out loud.

1. Fire up the Spotify app on your phone, laptop or tablet.
   Ok, fired up the Spotify app I downloaded from the Microsoft Store on my tablet
2. Play a song and select
   Yep I play a song and tap on "Devices Available"
3. Select your device and start listening
   No devices are showing. It only says "connect to a device" including "start Spotify on another device and it will magically appear here" but how do I start Spotify on my Chromecast???

[BSLMarketing]

Hi, still looking for assistance with this please.