XinputDotNetPure and XInputInterface: They work flawlessly in Editor, but Standalone build can't find them.

I created a test build of my game in Unity 5.3.4p6 to test it in full resolution. I use XInputDotNetPure.dll and XInputInterface.dll in my project to allow 4 controllers at once.

XInputDotNetPure.dll is set as Managed while Interface is set as Native. I configured them both to only work on Windows (not Mac or Linux) in both Editor and Standalone. In the editor, it works great. I get zero warnings or errors whatsoever.

But when I try in the standalone exe, it's a whole different monster. It can't find XInputInterface.dll, (fails to load it actually) despite it being present in the Plugins folder in test_Data. I checked my output_log.txt file, and I get this inside of it:

Failed to load 'C:/Users/Nick/Downloads/misc/FEUD/Feud Test Build/TEST_Data/Plugins/XInputInterface.dll', expected 32 bit architecture (IMAGE_FILE_MACHINE_I386), but was IMAGE_FILE_MACHINE_AMD64. You must recompile your plugin for 32 bit architecture.

It also throws a bunch of ArgumentOutOfRange exceptions (due to my XInput controller List being null, I assume)

I don't know anything about Windows architectures, so is there anything I did wrong?