It should be noted that only drives with HDD Size 2.5 "(9.5mm HDD / SSD) can be installed here. Thus, currently a maximum of 1TB is possible. My ordered 2TB drive I had to return because it was thicker than 9.5mm.
What bothered me was to find this limitation either in the item description in the manual. I found only on the Zalman website under technical specifications in the product details.