You only need to upload a WAV file (16bit / 44100 Hz) for distribution, any other file formats (AIFF, FLAC, etc) will not be accepted. All WAV files must be appropriately mastered and of a high quality, failure to do so may result in the stores removing your track(s) from their platform.
Once your release is approved, the WAV file you supply will be delivered to the stores who will convert it on their end to the various audio formats they offer for sale/streaming/preview.
For more information on uploading your releases, please see the following articles: