Hi,
BoxCryptor Portable does not provide a virtual drive to access your files. For the file system integration using a virtual drive, BoxCryptor has to install a file system driver which requires administrator privileges. As the portable version should run on any computer without installation and without administrator privileges, we can't install this driver.
You can read/write files by "dragging and dropping" the file from the BoxCryptor Portable window to Windows Explorer and vice versa.
Best regards,
Robert