First, you need to select a proper "paper size" in MS PowerPoint, not in PDF Driver.

Secondly, select "DocuCom PDF Driver" in available printer list, and then choose "Printing Preview" to see if there are still some white margins in generated PDF.

If the preview result is ok, you may print the "PPT" file to "DocuCom PDF Driver" Printer, and then get a PDF without cropped text.

Note: PDF Driver use the page settings (paper size, orientation, resolution, scale...)of the Application (such as: MS PowerPoint) only.
For example: If you select "A4" in MS PowerPoint, and select "B5" in PDF Driver, you will get a PDF whose paper size is "A4" (210*297mm).