"mbps" is a meaningless abbreviation. You need to consistently and correctly use capital letters when communicating technical terms. You cannot "e e cummings" your way into effective writing.
500 megabits per second works out to 5.4 terabytes per day. No idea where you get 1.5, unless you were thinking of 500Mb/hour!
60 × 60 × 24 × 500 × 1000000 ÷ 8
but 500 megabits per second to me is 500mbps?
ie. my cablemodem is 100mbps which is 100 megabits per second?
and that would [make Roman] 5.4 Terrabytes aka 5.4TB per day
but the transmitter is not at full speed full power 24/7
so it is 1.5TB per day in documentation that I do not have handy but vaguely remember
to repeat the more amazing part is that is from a MILLION MILES away, wow
(JWST "only" does 23mbps, 23 megabits per second)
Does it stop making sense when your calculations for the Roman telescope indicate slower speeds than your connection, which you say is 1/5th the speed?
Now, since the Roman telescope will be at an L2 point, signal acquisition will always be subject to the Earth's rotation. So there will be multiple ground stations involved across the globe.
https://en.wikipedia.org/wiki/NASA_Deep_Space_Network
If the quoted rate by NASA of 1.5 terabytes per day is accurate, then it will not be downlinking 24/7, but in bursts. 500Mbps is also the max, where the actual range will be 250-500. We'll need to account for RFI and packet loss, etc.