macOS Catalina doesn't allow MAMP permission to certain folders (Documents, Downloads, Desktop)
Catalina has more restrictions on system folders which we can apply an exception:


Open System Preferences -> Security and Privacy -> Privacy tab -> Full Disk Access -> Press 'Unlock to make changes' padlock
Open Finder Window -> "Go" menu -> "Go to folder" -> type "/usr/sbin/"
Drag the file "httpd" to the list inside the Full Disk Access settings.
Restart Mamp servers