Swanstone Base Installation 

The drain pipe is cut so the top is just below the shower pan. There is a supplied rubber drain seal that slides into the shower pan and over the pipe. That's all, there is a supplied drain screen that also snaps into place.

No connections, just the rubber flange pressed against the drain pipe and pan outlet?

There is a supplies rubber gasket/seal that slides over the pipe and into the pan drain.

There is a rubber gasket/seal that fits into the pan drain opening and over the pipe. There isn't any other screw down flange needed. It's just a slip fit seal.