The file is not meant to be downloaded solo. Getting it from any site other than Capcom (or your game distributor) is like picking up a USB stick off the sidewalk and plugging it in. Just don’t do it.
The original game relied on GFWL, which is now defunct. While Steam has patched much of this out, some users still need the xlive.dll "cracker" or dummy file placed in the same folder as re5dx9.exe to bypass the check. re5dx9.exe download
A Launcher.exe file was included to let players switch between these two versions. However, when the game was later converted to use Steamworks (replacing Games for Windows – LIVE), the DX10 version was removed. In many modern installations, the launcher has become redundant, and re5dx9.exe remains the main file for launching the game. The file is not meant to be downloaded solo