There is a separate category for streaming and non-streaming, probably due to the restrictions on non-streaming formats - I imagine Supergirl would be a very different series if it was made for a streaming platform like Netflix or DCU.
I don't know who won the Best Streaming Superhero Television Series award. I've not seen any articles saying yet.
Full list of Nominees:
Best Superhero TV Series
Arrow
Black Lightning
Marvel’s Cloak and Dagger
DC’s Legends of Tomorrow
The Flash
Gotham
Supergirl
Best Streaming Superhero TV Series
DC’s Doom Patrol
DC’s Swamp Thing
Marvel’s Daredevil
Marvel’s Jessica Jones
Marvel’s The Punisher
Marvel’s Runaways
The Umbrella Academy
https://www.slashfilm.com/2019-satur...s-nominations/