Did you already purchase the design? There is usually a place in your account to select the format for download. The company may be able to send you the design in PES format.
FYI tips if you change the format:
Check the size and stitch count before you make any format changes. Re-check the size and stitch count after changes. Also check that all the thread color changes transfer into the the new format. You may want to make a sample stitch out before the final stitch out.