As mentioned, Tablo formats the drive as EXT4 (or EXT3 depending on how long ago the drive was connected). Those are both Linux file systems.
You have 3 options.
#1. Use one of the tools in this section to offload the shows from your drive to your computer and start fresh with the new drive. You wont be able to view them on the Tablo but you can still view / save them elsewhere.
#2. Check out this thread where it gives you a few ideas of how to read the drives through windows, either via loading a driver or booting from a Linux bootable disk or drive.
#3. If you have access to an old PC or laptop, you could just go ahead and load a linux OS of your choice.
Personally I suggest #1 or #3.
#1 has the least risk and there is something freeing about starting fresh. Its probably the most stable option as well, less chance of bugs or corrupted transfers.
#2. I have successfully completed when I moved from a 1Tb to a 4TB. I even successfully moved from the older EXT3 to EXT4 in the process without any known issues. However, it was extremely SLOW and it was a bit buggy, taking me a few tries to get the drives to mount and begin transferring. A few nail biting moments with errors early on.
#3. This is the path I went down when I moved from a 4TB HDD to a 4TB SSD. I grabbed an old laptop, installed UBUNTU and after Tablo formatted the second drive, it was an easy direct copy. As a plus, it brought new life into an old laptop that was struggling with Windows 7 but UBUNTU runs great on it.