Attaching Elfa system to unevenly constructed interior wall

[Sviddeb]

I plan to mount an Elfa system with a top track in a walk-in closet but I'm unsure of the best way to attach it. This is because I'm not quite clear on how the inner wall is constructed.

The wall is 253 cm wide and there's a metal ceiling track and floor track. However, there aren't really any studs, only a type of "lath" with a thickness of about 15mm to which the single drywall is attached. The lath is mounted with 45 cm spacing and the drywall panels are 90 cm wide.

Could it be best to attach the Elfa system's top track to the ceiling track with a type of metal screw? And then place the wall uprights at 45 cm intervals and attach them to the lath. Or is there another smarter solution?
Thanks for the help and good ideas ☺️

 

[tergo]

This as I can't really understand how the inner wall is constructed.

probably with standing steel studs 38 mm wide, you can screw into them with drywall screws or a sharp wood screw

 

[Sviddeb]

Hello.
Unfortunately, there are no standing steel studs. I have searched with a stud finder and also with a magnet. The only "standing" thing is the thin batten to which the drywall is attached.