Geeze, why all the redacting? Nobody cares what your VM's are named.
It looks like /dev/sda is set up as a typical PVE storage. There are boot and efi partitions, /dev/sda1 & sda2. There is an LVM partition, /dev/sda3, with two logical volumes, "swap" and "root", that are used as the system swap and root partitions, respectively. The rest of the partition is configured as an lvm-thin called "data". That's about 610 GB of block storage and is where you would normally put your VM disks. In the GUI these show up as "local", for the root volume, and "local-lvm" for the data volume.
On the other hand /dev/sdb is just a disk that isn't partitioned. Did you format it with a filesystem using "mkfs"? Is there anything already on it?
Moving on, "Disk" is the name of a directory storage you created. Based on the error message you told PVE that a volume was supposed to be mounted on /mnt/pve/Disk, but there is nothing present. Maybe you mounted it by hand and never added it to /etc/fstab? It is hard to say. It would be helpful to know what steps you took to add "Disk" in the first place.
Assuming that you did format /dev/sdb with a filesystem, you could mount it like this:
mount /dev/sdb /mnt/pve/Disk
If that works, add it to /etc/fstab so it gets mounted when the system starts:
/mnt/sdb1 /mnt/pve/Disk ext4 defaults 0 1
If that doesn't work, then you will need to partition and format /dev/sdb first, then follow the previous steps. Note that this will destroy any data that's already there.
