Go to "Notification Settings" tab on "Settings" page.

Email Settings:

• Jobs Notifications Recipient - email address that will be used to send notifications from Work-Relay background jobs. By default, this is the email address of the user who started a job.
• Email Delivery Contact -  this is needed for the "Send Email" action when you want to use a standard Salesforce email template in order to send an email from Apex code using a Salesforce email template and you want to pass a record as context to that template - you must send an email to a Contact (standard Salesforce object). That's why you need to specify the helper Contact on the Work-Relay Settings page.
• Enable Email Assistant - enables Email Assistant that allows users to proceed process steps via replying to emails with step notifications.
  

Chatter Settings:

• Enable Chatter Assistant - enables service allowing user to proceed steps by commenting Work-Relay chatter feeds.

See proper article about Chatter Assistant.

Canvas Settings:

Via Canvas Settings user can insert canvas application to the chatter feed:

• Api Name - canvas application Api Name.
• Title - title of the iframe within the chatter feed.
• Height - height of iframe in pixels.

SMS Settings:

Via checked "Enable SMS Assistant" user can insert Twilio service credentials:

• Twillo Account SID
• Twillo Auth Token
• From Phone Number

Slack Settings:

To make Slack notifications available you need to configure them once.

First, get a WebHook URL from Slack. Go to your Slack App directory -> Manage -> Apps -> Custom Integrations -> Incoming WebHooks (1):

Click "Add to Slack" button:

On the next step choose a channel (2) and click "Add Incoming WebHooks Integration" to get WebHooks URL:

Copy URL and add it to Slack Settings for Work-Relay.

Open "Settings" tab, go to "Notifications settings" subtab (3) and click "+" button (4) to add new Slack channel. Fill in "Name" of Slack channel and paste Webhook URL provided by Slack App.