Travel policies (located under Power Tools) are entirely optional - they are not required for planning travel.
NOTE: Before you can effectively set policy for your company, you'll need to create Traveler Groups (at least one), if you haven't already done so during Setup.

The travel policies for your company might include things like preferred airline carriers, limits on car rental car type, and preferred hotel properties. When you set a policy for your whole company or a Traveler Group within it, those preferences are taken into account in search results when travelers and agents search for flights, hotels and cars. For example, your company may have designated one or more preferred air carriers, and those will be the flights sorted to the top of flight results when you do a search.