First decrypt the drive. When I plugged it in GNOME displayed a dialog and asked for the key. I’m guessing that cryptsetup luksOpen /dev/device device_crypt would work as well.
Run lvdisplay to get the LV Path for the logical volume that you want to mount.
Then, activate the volumes , there is a way to activate a specific one volume, but the following activates them all.
vgchange -ayThen mount it
mount <lv-path> /mnt