The file 'IKEA VICKLEBY Floor Lamp Foot Joint 3D Printer Model' is (stl) file type, size is 61.5KB.
The original plastic joint breaks easily when you remove the feet couple of times, the lamp wasn't really designed to be disassembled.
I printed it with ABS without supports, see the photo. Holes are for optional screws but even without them the fit is tight enough to do the job.
The source design is available on Onshape
foot_joint1.stl | 239.2KB |