Lena/Cadmus took Supergirl to the facility after they put the helmet onher. Once Jerimiah helped her escape. She could go outside look around/figure out where she was.

I assume she followed a sonic signal.
I think the bigger question is how Cadmus heard what Supergirl was saying. They presumably broadcast on a frequency which only she could hear (which has been don before). But how did they hear Supergirl's response when she's just randomly flying around.
Unless Alpert's covered in bacon grease, I don't think Hugo can track anything.

Yes, I know that she was lured there, but she wasn't given an address. Not that we saw. Maybe they didn't need to give an address? They sometimes given an address, or they do on the Flash.

I think it obvious that she used the super hearing to find where it was coming from. She just followed the voice.

Heavily implied? I thought Lena didn't know about her mother?

She was "invited." We didn't get to see it on screen, but it was heavily implied that Lena gave her the location while en route.

but how did SG know where Lillian was?

Lured there of course. its pretty obvious

but Lillian didn't give SG the address right? i too wondered how SG just "knew" where Lillian/Cadmus was in that scene.

She was lured there by Lillian Luthor.
"By law you have to call it a lair if you use it to torture people." Douglas Davenport

That was at the end. I'm sorry, I meant when she went to get Mon-El? I don't think that she knew at that point.

Because she'd just escaped from there. She just took them back to where she ran from.