If the macOS installer can't create a recovery system on your disk, it might allow you to continue the installation, but warns that some macOS features aren't supported or won't be available, or that a recovery system can't be created. That can happen in these circumstances:
- You're installing on a disk that is part of a RAID set, which the macOS installer doesn't support. To use the disk as a startup disk, first erase the disk so that it's no longer part of a RAID set, then reinstall macOS.
- You're installing on a volume that contains a Boot Camp partition modified outside of Boot Camp Assistant or added after using Boot Camp Assistant. To resolve, erase the disk, including the Boot Camp partition, then reinstall macOS and use Boot Camp Assistant to create a new Boot Camp partition.
You don't need a recovery system to install and use macOS, but without it you can't use FileVault, set up a firmware password, or use Disk Utility to repair the disk.