IMPORTANT: If you do not have access to the OAuth Apps, please contact Happeo support throughthelp.happeo.com
You can create an OAuth App with Happeo if you are an admin. The apps can be created by accessing the admin panel and selecting the API management tab and from there select OAuth.
From here you can select to Create a new OAuth App.
You'll then need to add all the necessary information to obtain the client secret.
NOTE: Once you have created the app the first time. The Basic Information page will have additional settings for the default token expiration. These will appear under "Advanced Settings".