In case of issues related to Security & Privacy settings on macOS, such as:

• Inability to move files to trash (prior to v0.9.5)
• Inability to access the Downloads/Destkop/Documents folder
• Inability to access removable volumes

You should first confirm that access to those folders has not been denied. You can do this by opening System Preferences, navigating to Security & Privacy -> Privacy -> Files and Folders and making sure all boxes under muCommander are checked. You will need to restart muCommander for the changes to apply.

If that did not work, you may want to reset the Security & Privacy settings for muCommander.
In order to do that, you first need to make sure SIP is disabled.
The status of SIP can be checked with: csrutil status
If it is enabled, you'll need to restart the operating system and get into Recovery Mode (by pressing CMD+R on boot) and disable is with: csrutil disable

When SIP is disabled, you could use tccutil to reset the settings of muCommander.
To disable all settings run: sudo tccutil reset All com.mucommander.muCommander.
To disable the settings of a particular category run: sudo tccutil reset CATEGORY com.mucommander.muCommander
Where CATEGORY is one of:

• Accessibility
• AddressBook
• AppleEvents
• Calendar
• Camera
• Microphone
• Photos
• Reminders
• ScreenCapture (for the Screen Recording list)
• SystemPolicyAllFiles (for the Full Disk Access list)
• SystemPolicyDesktopFolder
• SystemPolicyDeveloperFiles
• SystemPolicyDocumentsFolder
• SystemPolicyDownloadsFolder
• SystemPolicyNetworkVolumes
• SystemPolicyRemovableVolumes
• SystemPolicySysAdminFiles

Note: if you disabled SIP at the beginning of the process you may want to enable it again. This can be achieved by running csrutil enable in Recovery Mode.