Direct in the Reason column of the statistics means the short link sent the visitor directly, without an ad. This happens because of the advertising type of the link or the plan of the link owner. It does not always mean that the visitor came without a referrer.
A blank Referer Domain means AdLinkFly did not receive a usable HTTP referrer. This commonly happens with typed or bookmarked URLs, some apps and documents, and browsers or sites with restrictive referrer policies.