The 'Into Lyne' step when added in a sequence allows you to 'Assign a user' to the step and as the campaign progresses, the 'Intro Lyne assigned task will show up in the assigned users 'Sales Inbox' as highlighted below.
This is what a Complete vs Incomplete Intro Lyne will look like under your 'Sales Inbox'
From here, the assigned user has the option to edit, approve and complete the 'Intro Lyne' task for each enrolled contact by clicking on the task (as mentioned in the description of the highlighted task in the screenshot above). In doing so, a pop-up with the generated Intro Lyne will show up from where it can be edited, approved & completed.
Note: If your sequence has another step after the Intro Lyne step, the sequence will only move to the next step once the assigned user has approved & completed the 'Intro Lyne' task under their 'Sales Inbox'.
Steps to Edit, Approve & Complete an Intro Lyne
Click on the task highlighted in the 1st screenshot above and it will open as shown below.
From here, you can select the 'Type' and 'Variation' if a Followup, Question, or Statement from the dropdown options. On making your selection from both the dropdowns, you will notice that the variation in the grey-colored text box will change as per your selection.
You can also browse through the variations by clicking the arrow icons and clicking on the '+' icon highlighted in the screenshot above will add the variation to the text box below it.
A contact for whom an Intro Lyne is 'Incomplete', will not have the 'Type' and 'Variation' options to choose from but it will have different ready-to-use template variations to choose from by clicking the arrow icons. (See the below screenshot)
Once the variation is added to the below text box, it will look as shown below from where you can make any edits by clicking within the text box.
The last and very important step is to click the 'Approve & Complete' blue button. The Intro Lyne will only be approved and completed post clicking the blue button highlighted above. In doing so, the 'Intro Lyne' will be crossed out under the 'Sales Inbox' and the 'Intro Lyne' will be auto-populated to the existing 'Intro Lyne' field and can be viewed under the respective contact details page. (see the below screenshot)
An 'Intro Lyne' can also be 'Approved & Completed' from the contact details page. You can access the contact details page for the same pop-up shown in the screenshot below by clicking on the 'Contact Name'.
Note: Changes to the 'Intro Lyne' can be made anytime manually under the 'Contact Details' page or via the same task received under the 'Sales Inbox' of the assigned user.
Refer to this article on the steps to Approve & Complete an Intro Lyne from the Contact Details Page.