Enderal won't work with the old 32 bit version of Skyrim, you need to have Skyrim SE (64 bit) which also includes all the DLC, an improved rendering engine, better lighting, and better stability. Back when SE first released, it was free if you owned the original game and all DLCs. Now, you'll frequently find it on sale for around $5.
Enderal: Forgotten Stories is a total conversion mod for Skyrim that is set in its own world with its own lore and story. It offers an immersive open world, all for the player to explore, overhauled skill systems and gameplay mechanics and a dark, psychological storyline with believable characters.
Enderal: Forgotten Stories (Special Edition) is a total conversion mod for Skyrim SE. It offers an immersive open world, new skill systems and gameplay with a dark, psychological storyline and believable characters. SE features a new rendering engine, improved lighting, performance and stability.
If you have the standard version of Skyrim just use the standard version of Enderal. You don't need to have Skyrim installed. It only needs to be in your library. Just add Enderal and install it like every other game.