Google Home Mini - Playing Music For Free ????

[Gizmonster]

So the missus got me a Google Home Mini for my recent birthday and I'm now trying to set it up ....... not as simple as it seems ......

I know it will do a plethora of things, but I just want it t play a specific song that I request. I have to connect it to a music service, such as Spotify, Youtube, Google Play Music and Deezer. All of these require a premium account; otherwise you can't play a requested song, it just plays a random song.
Does anyone know how to play a requested song, without having to pay for a premium account??

Also, on my phone on the Google Home app, under "more music services", there is the option, "you can ask your assistant to use any music app on your phone or tablet".
Well, I have a music app, where I have lots of albums downloaded onto my phone. I'd love to be able to access it so I can play these on my Google Home Mini, but can't figure out how to??

Anyone help with any of the above please????