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
Check Internet Explorer settingsQuicken uses functions and settings of Internet Explorer, even if you normally use another browser for your daily activities, so it must be configured properly. Please verify the settings.
Go into Control Panel / Internet Options or Start Internet Explorer. Click on Tools / Internet options.
Click the Advanced tab. Ensure that all "Use TLS 1.0, 1.1, 1.2" have checkmarks. Uncheck all "Use SSL x.x" Click the Contents tab and click the "Clear SSL state" button. Click Apply, then OK. Close IE. Close and restart Quicken and see what happens.