Casting Bug for Androiid LG G4

[SHiNi15]

Hey community-

I think I ran into a weird bug. I am trying to cast from my windows computer to my unlocked smartphone with Spotify pulled up. I need to cast to my phone because the bluetooth on my computer seems to be having problems, and because I use a free membership (sorry but money is really tight rn)  I still want to have the perks of using my computer for Spotify, as I am working from my computer.

Anyways, the PC Spotify application can see my device, but it tells me it is locked, which it is not, and that I need premium, which is currently not much an option.

My phone is an LG G4 unrooted, spotify is pulled up and updated, and they are sitting not even a foot apart.

Thanks for any help~

-Shini