Alfred will do the verification of your leads from your campaign automatically and it may take around 30 - 45 minutes for Alfred to approve the leads.
Alfred will work in the background to verify the leads. Once verified, leads will move from pending status to approved status, at which point will be added to the social sequence.
Note: The Cloud-based app must be within work hours for the campaigns to run. It will still verify the lead URLs even it is outside work hours but make sure you're LinkedIn credentials are connected under Integrations. It will not start to send any activity if it's not running within work hours.