I don't know if this is a bug in macOS or they changed how kexts are permitted starting with macOS 10.13 B4.
Here's the console log:
service[8670]: Kext rejected due to insecure location: <OSKext 0x7fc14a518e50 [0x7fffb0590260]> { URL = "prl_hypervisor.kext/ -- file:///Applications/Parallels%20Desktop.app/Contents/Library/Extensions/10.9/", ID = "com.parallels.kext.hypervisor" }
Rejecting invalid/inauthentic kext for bundle id com.parallels.kext.hypervisor at location prl_hypervisor.kext/ -- file:///Applications/Parallels%20Desktop.app/Contents/Library/Extensions/10.9/.
/Applications/Parallels Desktop.app/Contents/Library/Extensions/10.9/prl_netbridge.kext - no compatible dependency found for com.parallels.kext.hypervisor.
Rejecting invalid/inauthentic kext for bundle id com.parallels.kext.hypervisor at location prl_hypervisor.kext/ -- file:///Applications/Parallels%20Desktop.app/Contents/Library/Extensions/10.9/.
/Library/StagedExtensions/Applications/Parallels Desktop.app/Contents/Library/Extensions/10.9/prl_netbridge.kext - no compatible dependency found for com.parallels.kext.hypervisor.
Rejecting invalid/inauthentic kext for <...>