The error you are encountering is likely due to macOS's Gatekeeper security feature, which can block applications from unidentified developers. To resolve this, you can try the following steps:

1. Open "System Preferences" and go to "Security & Privacy".
2. In the "General" tab, you should see a message about Spine being blocked. Click "Open Anyway".
3. If the issue persists, ensure you have downloaded the correct version of Spine for your Apple M4 chip. Since the M4 chip is not officially mentioned, ensure you are using the latest Apple Silicon version of Spine, which should be compatible with newer Apple chips.

If these steps do not resolve the issue, it might be helpful to check if there are any additional security settings or antivirus software that could be interfering with the installation.

Prakash

Thanks for reporting this. Which MacOS version are you using? Probably the .pkg is put in quarantine by the OS.

Can you try the following?

1. Open the .dmg
2. Drag and drop the .pkg somewhere and copy the path to the .pkg.
3. Open the terminal and use this command to remove the quarantine flag to the .pkg file xattr -d com.apple.quarantine PATH_TO_THE_PKG.

Then you should be able to launch the installer.

Prakash

Ah! Aren't you even able to open the .dmg?
So, aren't able to reach this window?

Can you confirm that?

If that's the case, you might try to use the command above on the.dmg, once the OS error message appear. xattr -d com.apple.quarantine PATH_TO_THE_DMG. That should tell the OS the file is secure.