Cant sync Messages to conversation between my iphone and android users.

Hi brushwood,

Thank you for clarifying that for us. You'll want to set up text message forwarding to send and receive your SMS/MMS messages on your Mac.

1. Confirm you are signed into the same Apple ID for iMessage on both your iPhone and Mac. On your iPhone, go to Settings > Messages > Send & Receive. On your Mac, open Messages then go to the Messages menu > Settings ( or preferences depending on your macOS) > iMessages, confirm the Apple ID listed here.
2. On your iPhone go to Settings > Messages > Text Message Forwarding and enable for your MacBook and Mac mini

Check out: Forward SMS/MMS text messages from your iPhone to your Mac or iPad - Apple Support

Have a good one!

Hello brushwood,

We'd like to learn more about your goal, so we can help answer your question.

Can you let us know more about your goal? For example, are you wanting all the messages you send, receive, and delete to be updated across your devices? Which app are you using for those messages?

That information will help us determine how to proceed.

1. You can use Messages in iCloud, but that applies to messages in the Apple Messages app, on Apple devices. 

You can find more information about Messages in iCloud and the requirements to use that feature here: Access your messages on all your Apple devices

When you use Messages in iCloud, all the messages you send, receive, and delete are updated on all your Apple devices automatically. Keeping your messages in iCloud also helps you save space on your Mac.

To use Messages in iCloud, you need macOS 10.13.5 or later, iOS 11.4 or later, or iPadOS 13 or later. You also need to be signed in to iMessage using the same Apple ID on every device where you want to use Messages in iCloud.

2. If you're using another app for messages on your Apple and Android devices and want to confirm syncing options for the app, you may want to reach out to the app developer for assistance. This link can help you get in touch with an app developer: How to contact an app developer

Thanks!

Great brushwood,

We hope you have a great day.

Cheers!