My girlfriend has a moto g2 with android 5.0.2 and is able to see chromecast as a device.
I have a moto g3 with android 5.1.1 and I can't see the chromecast device.
both our spotifiy apps are at the same version (184.108.40.206.0.0).
She is using the free version, I am on premium paid version.
we are using the same wifi and the same chromecast 1st gen.