Your fdisk output shows a single partition of type ee which according to https://en.wikipedia.org/wiki/GUID_Partition_Table is the type for the protective MBR partition shown by MBR tools when looking at GPT partition tables.

Try using gdisk -l instead of show the GPT partition table.

i have a some sata->usb adapters/enclosures/docks that can't be used with > 2tb drives or with 4Kn (native 4k sectors, no 512 emulation) drives. i also have a 2-bay cheap nas that can only do 2x1tb or smaller and there's no new firmware or hacks to 'fix' it even though it's linux under-the-hood.

start with hooking it back up to sata to copy anything on it you want elsewhere, check the filesystem, and run the extended diagnostics.

Commenting because id also like to know.

In my case I resorted to using another enclosure/ adapter

I have no experience in this specific matter, but you could look up how to switch the sector size from 512 bytes to 4096 and, you know, just do the opposite.

I think the first time you are trying to mount the drive and not the partition "sudo mount /dev/sdc /mnt" and on the second and third attempt have the sdc1 right, but need to make a folder under mnt to mount the drive onto. Make a folder like 'tempdrive' under /mnt and then try it with this since you said it was an ext4 filesystem. Note, you can name it whatever you want I just picked that as an example:

cd /mnt

sudo mkdir tempdrive

sudo mount /dev/sdc1 /mnt/tempdrive

If it doesn't recognize the filesystem then use -t

sudo mount -t ext4 /dev/sdc1 /mnt/tempdrive

And yes, once you get it down, an fstab entry will make this mount every time, but I would use the uuid in the fstab. I have two mounted on a machine like this in my /etc/fstab:

UUID="6a95603a-2112-4c4d-ad4d-e146e646a74a" /media/largedrive ext4 auto,nofail,noatime,rw,user 0 0

UUID="3E31-540B" /media/new4tbdrive exfat auto,nofail,noatime,rw,user 0 0

I noticed in all of this that you haven't done a fsck on the partition yet. This will tell you more than fdisk and likely fix the problem for you.

How is the disk formated? NTFS?

Did you try simply mounting /dev/sdc1 without the extra arguments? You also need to make a mount folder in /mnt, so

sudo mkdir /mnt/mydrive

Then

sudo mount /dev/sdc1 /mnt/mydrive

Few years ago I had a collection of maybe fifteen old disks, which I wanted to get rid of, by means of recycling. First I wanted to check the content and then format all so I put them in an external enclosure. It turned out that some disks were unusable. A closer inspection showed that these were all a certain brand and type (Forgot whether it was Seagate or Maxtor or WD). These disks would probably still do fine in a desktop or server computer (Which I no longer had at home) but not with the external enclosure. Perhaps your enclosure is the bottleneck here as well.

Have you tried any GUI tools, e.g. Gnome Disks?

Looks like ee is legacy mbr type with an EFI entry right after it, it could be that somebody has solved mounting this if you deep dive. And maybe an additional package is needed. Buy are you able to remount to sata and just transfer data? becuase you would want to reformat this to a modern GPT and filesystem at some point. Or see if you can pass it through to an XP VM for data transfer.

Why were you using Windows XP? I don't think it was even optimized for such large drives