There are two gauges options available for this pattern, one is for DK and one for worsted. Given the variability in yarns, you can try for either gauge on either weight of yarn. Just make sure that the fabric you produce has the appropriate body/flexibility for a cardigan.
If you cannot achieve one of the two recommended gauge options, please adjust your needle size and swatch again. If you CANNOT obtain gauge after several swatches, it's possible that your yarn selection is too heavy or too fine for the pattern and you may need to select a different yarn option.