Create a mounting point sudo mkdir /mnt/usb
Identify the device sudo fdisk -l as /dev/sda1
mount manually sudo mount /dev/sda1 /mnt/usb -o uid=pi,gid=pi
unmount manually sudo umount /mnt/usb
or add it to /etc/fstab
to have it automatically mounted at boot
No automount happens when usb sticks are plugged in.
For usb devices add the nofail option to /etc/fstab
otherwise there will be a boot blockage of the raspberry when the usb device is not plugged in
/dev/sda1 /mnt/usb vfat defaults,nofail 0 2