Start by navigating to the Settings tab at the top of your online dashboard >> click on the Integrations tab:

Scroll down the list to the Workflow section >> click on the connect tab under the Slack integration:

You will be redirected to the below page >> click on Allow to connect the integration:

Once you click Allow, you will be redirected back to your Integrations page on your online dashboard.

Scroll back down to the Slack Integration >> you will be able to choose the specific channel you want your Activity to sync through to.

You can also choose which Activity you want to pull through to the specific Channel.

This is how the activity displays in the selected Channel: