Problema al instalar VirtualBox en MacOS High Sierra

Estoy intentando instalar VirtualBox 6.0.15 en mi MacBook Pro 13" de mediados de 2010 con High Sierra. El instalador llega a la "Ejecución del paquete scripts" con "Tiempo restante: menos de un minuto" - y luego se cuelga. Esperar 30 minutos no hace nada. En la consola, puedo ver en el install.log:

2020-01-24 22:15:44+00 Cloud installd[27429]: PackageKit: ----- Begin install -----
2020-01-24 22:15:44+00 Cloud installd[27429]: PackageKit: request=PKInstallRequest <4 packages, destination=/>
2020-01-24 22:15:44+00 Cloud installd[27429]: PackageKit: packages=(
2020-01-24 22:15:45+00 Cloud installd[27429]: PackageKit: Extracting file:///Volumes/VirtualBox/VirtualBox.pkg#VBoxKEXTs.pkg (destination=/var/folders/zz/zyxvpxvq6csfxvn_n0000000000000/C/PKInstallSandboxManager/46764F46-7766-4183-854A-79216CB03C11.activeSandbox/Root/Library/Application Support/VirtualBox, uid=0)
2020-01-24 22:15:47+00 Cloud installd[27429]: PackageKit: Extracting file:///Volumes/VirtualBox/VirtualBox.pkg#VirtualBox.pkg (destination=/var/folders/zz/zyxvpxvq6csfxvn_n0000000000000/C/PKInstallSandboxManager/46764F46-7766-4183-854A-79216CB03C11.activeSandbox/Root/Applications, uid=0)
2020-01-24 22:15:52+00 Cloud installd[27429]: PackageKit: Extracting file:///Volumes/VirtualBox/VirtualBox.pkg#VirtualBoxCLI.pkg (destination=/var/folders/zz/zyxvpxvq6csfxvn_n0000000000000/C/PKInstallSandboxManager/46764F46-7766-4183-854A-79216CB03C11.activeSandbox/Root/usr/local/bin, uid=0)
2020-01-24 22:15:52+00 Cloud installd[27429]: PackageKit: Extracting file:///Volumes/VirtualBox/VirtualBox.pkg#OSXFuseCore.pkg (destination=/var/folders/zz/zyxvpxvq6csfxvn_n0000000000000/C/PKInstallSandboxManager/46764F46-7766-4183-854A-79216CB03C11.activeSandbox/Root, uid=0)
2020-01-24 22:15:52+00 Cloud installd[27429]: PackageKit: prevent user idle system sleep
2020-01-24 22:15:52+00 Cloud installd[27429]: PackageKit: suspending backupd
2020-01-24 22:15:52+00 Cloud installd[27429]: PackageKit: Executing script "./preflight" in /private/tmp/PKInstallSandbox.fRMY1G/Scripts/org.virtualbox.pkg.virtualbox.8bFgh6
2020-01-24 22:15:52+00 Cloud installd[27429]: PackageKit: Executing script "./preinstall" in /private/tmp/PKInstallSandbox.fRMY1G/Scripts/com.github.osxfuse.pkg.Core.3YlHpP
2020-01-24 22:15:53+00 Cloud installd[27429]: PackageKit: Using trashcan path /var/folders/zz/zyxvpxvq6csfxvn_n0000000000000/T/PKInstallSandboxTrash/46764F46-7766-4183-854A-79216CB03C11.sandboxTrash for sandbox /var/folders/zz/zyxvpxvq6csfxvn_n0000000000000/C/PKInstallSandboxManager/46764F46-7766-4183-854A-79216CB03C11.activeSandbox
2020-01-24 22:15:54+00 Cloud installd[27429]: PackageKit: Shoving /var/folders/zz/zyxvpxvq6csfxvn_n0000000000000/C/PKInstallSandboxManager/46764F46-7766-4183-854A-79216CB03C11.activeSandbox/Root (3 items) to /
2020-01-24 22:15:54+00 Cloud installd[27429]: PackageKit: Executing script "./postflight" in /private/tmp/PKInstallSandbox.fRMY1G/Scripts/org.virtualbox.pkg.vboxkexts.fPelJc
2020-01-24 22:15:54+00 Cloud installd[27429]: ./postflight: /Library/LaunchDaemons/org.virtualbox.startup.plist

Y eso es todo. No hay nada más en el registro - y la instalación simplemente se cuelga. ¿Cómo puedo completar la instalación?