In order to send leads to your private Slack channel, you need to add Leadfeeder bot in Slack to the private channel.
NOTE: In the case, you integrated Slack with Leadfeeder before November 9th, 2020, please reconnect your Slack with Leadfeeder before adding Leadfeeder to the private channel. You can do that in your integration settings in Leadfeeder by clicking Reconnect.
Here's how to send Leadfeeder leads to your private Slack channel:
STEP 1: Go to the private channel’s details and click the three dots:
STEP 2: Select Add apps, search for Leadfeeder, and click Add next to it. Now you can send leads to the private Slack channel. Also, you can set up Leadfeeder to notify automatically about leads meeting your preset criteria in a custom feed.