If your installation fails by specifically stating any of the target directories are not writable or accessible:
Windows has a setting under System > Notifications called "Notifications". This needs to be set to "On".
But some IT pros have commented that there is an interesting behavior with this setting. They reported that:
•the setting needed to be turned off,
•then they had to reboot,
•then they had to turn the setting back on in order for it to take effect.
Without following this process, even while that setting was set to On, notifications were not being generated to alert the user to intervene and allow access, so the installation would just fail.