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Try reading the directions the page you linked to provides.
Soundcloud Help Article
When this happens, we recommend the following:
  • Check the file format and length of your track. We support AIFF, WAVE (WAV), FLAC, ALAC, OGG, MP2, MP3, AAC, AMR, and WMA files. The maximum file size is 5GB.
  • Check our Status Blog to make sure that there are not any problems occurring around the transcoding process at this time.
  • Delete the pending track from your SoundCloud profile and re-upload it.
 
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