Does there need to be a comma in "Outsource your content to Canada Copywriter a trusted provider of content for your digital marketing needs"?

You are correct, but for the wrong reason. The presence of a pause when speaking a sentence aloud might indicate the need for a comma, but not necessarily.  Also, every written comma need not result in a spoken pause. In this case, the words "a trusted provider..." form an appositive. They rename, clarify, and/or add detail to the concept of "Canada Copywriter".  Grammar rules require the two concepts to be separated by a comma. For a simple explanation with examples, read the "Commas" section partway down this post: http://grammar.quickanddirtytips.com/dashes-parentheses-commas.aspx. For a more formal explanation of appositives, see this: http://en.wikipedia.org/wiki/Apposition.

No. The whole sentence needs to be put up against a wall and shot. If Canada Copywriter is claiming to create engaging content, its description should be engaging, too. And that isn't!

Your author is wrong. The comma is necessary, as Michael Ames says. Don't be put off by the scary word "appositive"; a friendlier way to think of it is that everything after "Canada Copywriter" is non-essential. Non-essential phrases, aka nonrestrictive phrases, are set off by commas. And look, there's one in my previous sentence!

Canada Copywriter is the trusted provider.  That is, when you say "a trusted provider, you are repeating in new words what you just wrote ("Canada Copywriter").  You set off the repetition with a comma every time.  Examples:  "I want a strawberry, a little red fruit." "I twisted my ankle, the bit where the foot joints the leg."  "I ran a mile in forty seconds, a world record."  "Use Canada Copywriter, a trusted provider."