Congrats on your first ram purchase. From the link you provided, they had options for the different levels of rams (1500/2500/3500 etc), and for the 1500 they had options for the 1500 ds and dt. DS and DT designate the generation of ram, DT being 4th gen rams (2009-present as the "classic") and the DS being the new 5th generation (2019-present). You did not say which one you had, but if your avatar picture is of your ram, then you have the older style 4th generation DT "classic".
For future parts ordering, always look for the DT or "classic" designation. Or it may just be easier to order for a 2018 ram (pre 5th gen being offered so no confusion) to avoid possibly getting the incorrect parts. Also, for using the forum if you have the DT, I would suggest posting over in the 4th gen section. Tons of info over there since these trucks have been in production for 12+ years at this point and lots of helpful people.
It can be a little confusing to new comers since they make both the DT and DS concurrently, and I believe they are still making the classics as of the 21 model year.