Within the field mapping name your can enter the name of your drive which is added like this in the system.

The driver has to be used to define whether it is a CD/DVD drive (choose: CD/ISO9660) or an USB stick or drive (choose: VFAT/NTFS).

In the drop down menu local device drives are listed how they are shown commonly in Linux. As a rule the first USB stick or USB drive gets connected with the description SDB. Is there already a partition on the drive it shows up as SDB1. Choose the devices which shall be connected to the Thin Client. When configuring a card reader you have to choose a partition.
The descriptions without a number are common for dummy entries. You can still chose them, but you should choose the partition instead e.g. SDB1.

If the drive should be read only deactivate the option writable.

If you would like to share your drive on the network please activate the option share through samba.