Ripping with ROCK

I have plug my external CD driver in my ROCK usb.
I have roon 1.8. And external G-Drive USB hard disk 4 TB plugged usb to the Rock.
When I open it appears the message that my driver must be writeable and I can not further proceed.
In the instructions I read that first it will show the internal disk and after the external usb.
My external drive surely is writable i have put into it lots of files.
What can I do?

What is the drive formatted as?

When you say drive, do you mean my external hard disc library?

In case the format of hard disk is not recognized by the NUC I will not be able of changing the format of Hard disk after the whole music there.

The format say Mac OS