If the subfloor is wood waterproof it before using self leveler and before spreading mortar or adhesive.
Install shower over floor drain.
Installing a shower over a basement drain is relatively a simple project.
The most efficient and least expensive method of installing a basement shower without the need to break concrete is to install it over existing plumbing stub outs.
If you want to install a shower over a concrete floor a fiberglass shower stall will work just fine.
Fix an uneven floor using a self leveler.
Ideally you ll already have a drain roughed in with the pipe sticking a few inches above the floor.
If the floor is not level the shower pan will not be able to drain properly.
Otherwise you have to break through the concrete to run a new line for a shower stall installation.
This guide explains how to install a shower pan over existing plumbing.
Then install the membrane over the mortar bed and over the drain base and cut out a section over the drain hole in order to attach the center part of the drain on which the weep holes are located.