That PC looks like a great value with great specs. It is only a 90W power supply which would have been way too low a few years ago but I assume is OK now.
From a clutter standpoint you can add a 2nd 2TB HD to the inside rather than get another external. The internals are usually about $5-10 cheaper too.
The specs on their website say it supports this:
Storage Storage Support Up to 2 drives, 1x 3.5″ HDD + 1x M.2 SSD • 3.5″ HDD up to 2TB • M.2 SSD up to 512GB
