We have factory roof rails for our low roof van. But Fiamma says their roof mount awnings (F65s and F80s) will not fit the low roof. I've had one seller say it will fit but not really willing to spend lots of $$ only to find out it doesn't fit well or we really have to be creative on installation. Other sellers I've contacted says will not work.I'm looking for an awning for our 2019 144 high roof van. Fiamma looks like the most popular choice but I'd consider other brands too.
Fiamma makes brackets for Sprinters with or without rack rails. I'm assuming that your low roof van has the same roof rack channel and holes as our high roof van.