During download, mInstaller places its temporary files into the Download Directory. Once it's finished downloading, it will automatically install them into appropriate folders to make sure they are available in the target host apps. Temporary files are removed afterward.
This does not apply to Compositing Packs, AE templates, and LUT packs - these files don't need to be placed in any specific location, so they remain in your Download Directory. By default, the Download Directory will be located in your /Downloads/motionVFXDownload/. This can be changed to any other location by going to mInstaller's Settings panel, in the "Download Directory" section, clicking on the Browse button, and pointing to the target folder.