If you followed the instructions in post #2 for uninstalling, its likely you removed system Nvidia kexts that should probably be restored. If not don't worry, but uninstall the initial 10.13 driver release before updating. Uninstall incompatible kexts and those that cause library validation to fail i.e. graphics kext-patching. There is no requirement to enable SIP as shown by everyone who didn't. Or to approve the kexts when the 'team id' has already been added to the database or the entire kext-approval feature is turned off in SIP. The error/problem warning in the installer occurs before installation begins and can be ignored as well.