If you'd like to provide customers with a direct link to a campaign you've created, you can do so easily just by giving them the direct page link. To find the direct page link to one of your campaigns, click on the Marketing icon and then click on campaign builder.
Navigate to the campaign and click on it.
The direct URL for your campaign can be found directly above the campaign builder and below the breadcrumb at the top of the page.
You can get the link by right-clicking on it and copying it, or by clicking on the link and retrieving it from the address bar after it opens in a new window. This is also a good way to see a "preview" of what the campaign will look like.