If you haven't rebooted Windows since you installed the latest software update, please do so now and then try Quicken again.
Check if Windows Defender feature Ransomware protection is enabled. If so, configure it to add Quicken as an "allowed app" without turning off Ransomware protection. Perform the last step in:https://community.quicken.com/discussion/7857675/faq-windows-defender-controlled-folder-access