I managed to reproduce the error, in short your System Integrity Protection (SIP) is enabled, so "sudo mount -uw /" won't work. You can check in Terminal by typing: csrutil status
The new process involves 2 steps:
1. What you need to do is to enable the SIP, if you open clover configurator, mount your EFI, open config.plist (is in /EFI/CLOVER/ ), then under Rt Variables: CsrActiveConfig, change it to 0x67 (this will disable SIP), and restart.
- Disable SIP: 0x67
- Enable SIP: 0x00
- mine was originally set to 0x03 (partial)
2. After restarting, go back to terminal, and type: sudo mount -uw /
3. you may want to re-enable SIP after the post-installation.
Hope it helps!