USB not formatted on LS220D238

[bighunt15]

I'm working with a non-profit.
They have a LS220D238 NAS. Their old 2TB Seagate got full of their backups so they ordered a larger one.
The old exHDD worked fine. It just got full.

However, when I plugged it into the USB port, and tried to format to the Buffalo standard, it failed. And b/c the Buffalo can't correctly see the hard drive, the NAS can't back up to it.

I could format it on PC and my MacBook (even though I didn't).

Note: I'm new to NAS and the non-profit bought this NAS in 2019 (before i stated to work with them (i own a small computer business).

Any help would be appreciated!

Thanks.