First, create a stream for GoSquared for where you would like to receive GoSquared notifications and subscribe all interested parties to the stream. The integration will automatically use the default stream gosquared if no stream is supplied, though you will still need to create the stream manually even though it's the default.

Next, go to the Zulip settings page and create a bot named GoSquared. Go to the account settings page of your GoSquared account and under Project Settings > Services > Webhook > Add New. Add the below URL under the section 'Enter a URL to receive requests:' and name the integration, Zulip.

{{ external_api_uri_subdomain }}/v1/external/gosquared?api_key=abcdefgh&stream=gosquared

Note: api_key must be reconfigured to be the API key of your Zulip bot.
If you want to change the stream default that receives notifications, change stream= in the URL.
To change the topic displayed by the bot, simply append &topic=name to the end of the above URL. Where name is your topic.

Under notifications of your GoSquared account page, press Add New Notification and select when and why you want to be notified through Zulip. After you're done, remember to check the box of the webhook corresponding to Zulip.

Congratulations! You're all set
Your messages should look like this: