To use a two-column layout, you can just format the required portion with two columns. As you'll note, however, in your document that immediately pushes the two-column content to a new page. That's because you have some footnotes attached to the single-column Section. For whatever reasons, Word doesn't support having footnotes for sections with different column setups on the same page. There is a workaround for that:
1. Move the footnote references into the start of the two-column Section.
2. At the original footnote locations, insert formatted cross-references to the corresponding footnotes.
3. Format the moved footnote references as hidden text.

Depending on what you want to achieve with the table, you can either put section breaks either side of it or put it into a textbox, so it retains a full-width layout or you can uncheck the 'allow row to break across pages' option and format the paragraphs with the 'keep together' and 'keep with next' attributes (you might want to omit the 'keep with next' attributes for the last paragraph in each column).

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Cheers,
Paul Edstein
[Fmr MS MVP - Word]