New phone, Android and iTunes

[voodoopenguin]

I have a new phone, a Motorola Moto G5, which will be fine for what I need. I cannot in any way justify the cost of an iPhone. My previous phone was "smartish" but I never really took advantage of that as calls and the occasional text was all I needed, I had my iPad for anything else. This one has a bigger screen so I'm looking to see if it can be used more and one of the things I wondered about was playing music. My son-in-law visited today and he started to look at it after I asked what app would play music. I was told "Play Music" was the one so I then said how does my music get to the phone. Daughter and son-in-law started by saying about linking to the iMac and dropping music files across. I asked where to and s-i-l opened up the music library and was surprised to see my entire iTunes already listed. I'm not going to argue or worry but I did wonder how a Google Android phone had managed to access my iTunes library. I'm guessing it's a Cloud thing and my Google account was given permission at some point but can anyone tell me where I must have allowed that? I'm happy as the volume can be that much higher than my well loved iPod Classic and with my hearing loss that is a definite plus.

Paul