Shot in the partial dark: Doctor Who: The Creature from the Pit, originally airing in November 1979.
I know the creature was in like a dark room
and people would be drawn to it
From the Tardis fandom ("Tfan", subsequently) page for this episode: "The plate [A McGuffin (warning, TvTropes link) the Creature is seeking] activates and Torvin and Edu fall under its hypnotic effect." ... "The hypnotised Torvin and Edu approach, still carrying the plate, which they place on the creature."
and soon they were pulled in underneath it.
Tfan: "the creature squashes the Doctor" and "[the Creature has] his revenge by crushing Adrasta to death".
The Creature (Erato)'s page at Tfan: "However, as he did not eat people, they either died of fright or were crushed under Erato's weight."
I know the creature had long tentacle like structures come out from it.
A different Tfan page: "They had no true limbs, but had two large pseudopods. One pseudopod was shaped like the letter Y, while the other was simply a large tube."
I think it made oscillating sounds while people were being sucked in.
I can't think of a sound effect from the Tom Baker run of Doctor Who that fails to match this description.
Then when it was done consuming them, they then would be shot across the floor sliding far away from it, all dried up and maybe covered in a film.
You might be describing the victims of the antagonist's (plant-based) goon squad, the wolfweeds. From that page, "They appear to be predatory and are able to produce a web-like substance to immobilize their prey."