Hi CK1Sydney,
Thanks for contacting Apple Support Communities!
We understand that you're unable to play music on your Windows based computer.
Can you tell us which app you're using to play music? Are you using Apple Music on the web via a web browser? If so, you may need to upgrade Microsoft PlayReady so that you can access your content. This article explains in detail: About Apple Music Digital Rights Management for Microsoft Edge and Internet Explorer - Apple Support
Content owners use Microsoft PlayReady content access technology to protect their intellectual property, including copyrighted content. This service uses PlayReady technology to protect certain content. If the PlayReady technology fails to protect the content, content owners may require the service to restrict or prevent the delivery of protected content to specified devices or PC software applications. In certain cases, you may be required to upgrade the PlayReady technology to continue to access the service’s content. If you decline such an upgrade, you will not be able to access content that requires the upgrade.
You can reference this link which explains how to listen to Apple Music via the web and in apps: Listen to Apple Music on the web and in apps - Apple Support
Listen to Apple Music on the web
1. Go to music.apple.com.
2. Sign in with the Apple ID and password that you use with your Apple Music subscription.
After you sign in, you can:
• Access and play music from your music library.
• Browse and play music from the Apple Music catalog.
• Get your Replay Mix to see the top artists, albums, and songs that you've listened to so far this year.
We look forward to your reply.
Cheers!