If the client already has GTM installed on their site, this process should be as easy as creating a new tag, dropping in the configured integration script, selecting which pages it will trigger on and then publishing it
Here’s a few articles featuring similar steps to install their widgets:
https://getsitecontrol.com/help/install-via-google-tag-manager/
https://widgetwhats.com/blog/how-to-do-it/how-to-insert-widgetwhats-with-google-tag-manager/
Example:
Go to your Google Tag Manager account
Click on “New Tag”
Click on “Tag Configuration” and select “Custom HTML”
Copy the code below of alternate method and paste in the HTML section
Replace
"my_widget_ID"
with your widget ID numberClick on “Triggering” and select “All Pages”
Set your tag name (e.g. WidgetWhats Script) and Save