macOS has significantly enhanced the security & privacy protection, therefore it requires re-authorization when using Remote Mouse or a specific feature for the first time under macOS, otherwise Remote Mouse will not be able to work. This is very similar to how you authorize an app on the iPhone.

Accessibility

The first time to use Remote Mouse after connecting to the Mac, you will be prompted to grant access.

1. Choose "OK" to open the Accessibility window.

2. Click the lock icon in the lower left corner and enter your Mac password to unlock it.

3. Tick Remote Mouse in the list on the right.

Automation

There's no need to manually add Remote Mouse to Automation, as it will be requested automatically by the system when needed.