how to implement single sign on between MS CRM Online 2016 form button click calling 3rd party Azure web application [public domain]

Hi All,

Here is the requirement

1. We are customizing MS CRM online - 2016
2. In CRM form, I need to add a button and on click need to pass quote infornation to 3rd party service
3. 3rd party service which will redirect to a 3rd party website listing products
4. user can configure products in the web page

5. call CRM service and update products in CRM

Here I need to implement Single sign on while calling 3rd party service in crm form button click

Please do let me know details to implement Single sign on. Thank you.

Pre - requesties exist
CRM online subscription
Azure Portal subscription
Web service and web application are hosted in Azure web server  accessible from internet