Currently the Clevo has Ubuntu/Mate installed as root on the SSD. There is nothing on home, the HHD.
That is because Ubuntu was set up with a Home
folder under the / at /dev/sdb2.
You may want to check within eg Documents, Downloads, Pictures and Videos and see if there is data you wish to keep, and safeguard it, because you will lose that Home and its contents with the Zorin install.
I would advocate the following plan (yours, revised)
Make a bootable stick from the Zorin ISO file, (done and tested)
Insert the stick and boot up from BIOs, f2 on my machine
Select “Try Zorin” and connect to the internet
Select “Install” and “Something Else”
Select /dev/sdb, (no number) in the menu that features "drive or destination to install bootloader to"
Select /dev/sdb2 (currently Ubuntu root), there will be a list perhaps defaulting to Do Not Use This Partition, click for choice and scroll to top, select EXT4 Journaling System
Choose Format Partition (this will erase Ubuntu)
Choose / from next list of choices that appears, this will make /dev/sdb2 Root
Create a 512 Mb, FAT 32 partition for UEFI, (is this in a drop down menu?)
- no need, already created
Select /dev/sdb1, if need be choose Use Existing Partition
Choose Format to get rid of Ubuntu data from /dev/sdb1
Choose /boot/efi from next list if not defaulting to that
Create a 2 Gb swap file, Ext4
No need - see my comments on Zswap and swapfile, they will be used.
Use the remaining space on the drive to install Zorin, Ext2, (or Ext4???)
No need, you are using /dev/sdb2 for Zorin
Scroll up the partitions until you find /dev/sda1 Home. Click its line, choose Format, then from list choose /home
Close out of Gparted
You are not in GParted, you are in the Installer known as Ubiquity.
Choose to install now - the Installer will show a summary of changes to be made, OK it.
If it prompts about no Swap set up, OK it to go ahead without.
Once the Installer completes, reboot, if it prompts you to remove the USB stick do so, otherwise just let it reboot into
Zorin
Done, and report outcome back here.
Cheers
Wizard