Make doesn’t have a module yet for this external service’s endpoint.
If the external service has a Developer API Reference/Documentation then you should be able to integrate the endpoints in Make using the app’s universal module (Make an API call) or generic HTTP “Make a request” module.
If the external service allows you to register webhooks, then you can create a trigger to wait for incoming webhook requests in Make using the generic Webhook “Custom webhook” module.
You can also suggest for it to be made in the Idea exchange. Don’t forget to search for it first, just in case someone already suggested it, so that you don’t end up creating a duplicate.
If you need assistance in setting up the app’s universal module, or the generic HTTP module, please provide additional information about what you have tried with regards to the external service’s Developer API Reference – how you are setting the connection up, what endpoint are you trying to connect to, and what errors are you encountering.