MacOS supports reading NTFS file systems by default, but that is irrelevant in this situation (you don't want to access your Win Audiophile drive from MacOS to e.g. see it in Finder, but rather access it from your virtual Windows machine).

There should be no problems mounting a Biab external hard drive and run Biab from it within your Windows virtual machine (I have been using Biab extensively that way for some 10 years).

When you plug in a USB device while you have a virtual machine started, Parallel by default should display a dialog asking you whether you would like to mount the USB device in your virtual machine or in MacOS. Don't you get that dialog? Choosing to mount it in your virtual machine, it should show up in Windows Explorer after a little while. It is also possible to explicitly mount a plugged-in drive ( from the menu, choose Devices | External Devices | <Your usb disk>).

If you don't see you USB drive in Device | External Devices, it means Parallel Desktop doesn't see it. In such a case, I would first try plugging the drive into another USB port (I guess you have at least 2?), or try another usb cable. Also make sure that the external drive starts up (if it is powered by the USB cable, you might need to use a dedicated cable which uses two USB ports on the Mac (where one is used just to provide the extra power needed). On some of my external drives, there is a little led that turns green once the drive has started up correctly.

Good luck!

/Björn