I have a 128GB external usb drive attached to Zorin OS18 CORE machine. I initially dedicated it to TIMESHIFT. All seemed to work well. I recently decided to move a few files to that drive along side timeshift. Wouldn't happen. I believe it had to do with permissions .... and the drive was read only. From what I have researched, I think it's a 'simple' unmount, chmod command, and a mount command but I'm not good at those commands. 
Is this any help to GETTING some help in adding a few files to the timeshift drive? I don't see a 128GB device below:
$ lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINTS
loop0 7:0 0 66.8M 1 loop /snap/core24/1243
loop1 7:1 0 91.7M 1 loop /snap/gtk-common-themes/1535
loop2 7:2 0 48.1M 1 loop /snap/snapd/25935
loop3 7:3 0 4K 1 loop /snap/bare/5
loop4 7:4 0 395M 1 loop /snap/mesa-2404/1165
loop5 7:5 0 1.7M 1 loop /snap/gnome-system-monitor/193
loop6 7:6 0 66.8M 1 loop /snap/core24/1267
loop7 7:7 0 50.9M 1 loop /snap/snapd/25577
loop8 7:8 0 669.8M 1 loop /snap/gnome-46-2404/145
sda 8:0 0 931.5G 0 disk
├─sda1 8:1 0 512M 0 part /boot/efi
└─sda2 8:2 0 931G 0 part /
or
owner@Acer-Zorin:~$ df -h
Filesystem Size Used Avail Use% Mounted on
tmpfs 781M 14M 768M 2% /run
/dev/sda2 916G 23G 847G 3% /
tmpfs 3.9G 53M 3.8G 2% /dev/shm
tmpfs 5.0M 0 5.0M 0% /run/lock
efivarfs 100K 79K 17K 84% /sys/firmware/efi/efivars
/dev/sda1 511M 6.2M 505M 2% /boot/efi
tmpfs 781M 152K 781M 1% /run/user/1000
/dev/sdb1 117G 20G 91G 19% /media/owner/e32c1324-4179-4993-a179-762af0e63b20
owner@Acer-Zorin:~$
Thank you in advance for any help.