To sync data from WordPress to Intercom, you first will require the Intercom Sync by Highways plugin. This plugin is available, for free, in the WordPress Codex or via your plugin installer dashboard.
Once downloaded, install and activate your plugin and navigate to Settings then Intercom Sync
On this page, you have two options to connect the plugin to Intercom. The recommended option is via OAuth by simply clicking Connect Intercom. If you are a developer, you can create your own API key (See the end of this guide)
You will then be directed to Intercom and will be required to accept the access rights of the application:
Upon successful connection, you will be redirected back to WordPress and your API Key will be filled for you.
Note, you do not require an API key if you have connected successfully via OAuth.
Developer Connection & API Key (Not Recommended for Most Users)
If you are a developer and would prefer not to use the recommended option of OAuth, you can create your own private Intercom Application and insert your own API Key. Once inserted, click Save Changes on the Intercom Sync Settings page.
Note, Highways does not offer support for creating custom applications in Intercom and we recommend this option only if you are familiar with the Intercom Application workflow.