Yup, you must've missed the note from the bottom of the guide. Follow my E7450 guide Prerequisite section.
Note2:
Systems with Broadwell / Skylake / Kabylake CPU such as Latitude E7450 and Inspiron 5548, you'll need to set the DVMT prealloc to 96MB in order to bypass KP and to enable full graphics with full QE/CI. For more info, see here.