In order to integrate with SMSBump you will have to provide an api key. The api key can be found on the Sms Bump Integrations page.
On this page you should see the API key:
Note: If the above page asks you to login you can first access the Shopify app and then refresh the page. Accessing the SMSBump app in Shopify automatically logs you in on the site as well.
After you have the API key please choose SMSBump as the SMS provider in integration settings and add the API key.
You can further customize the SMS template, choose how many SMS to send for each order, choose if all your customer will receive an sms or only domestic customers.