To create an approval workflow for subscription creation with specific bundles, you have to create a new activity, a new workflow definition (that has the new activity), and a new rule associated to the new workflow.

1. Create a new activity which creates an approval task with desired role (role who can approve/reject the workflow). Steps to create new activity are available at: Customizing workflows.
2. Create a new workflow definition. Steps to create a new workflow definition are available at: Customizing workflows.
3. Add the activity (created in Step 1) into the workflow definition created in Step 2.
4. Create a new rule associated to the new workflow definition created in Step 2. This rule will check for the bundle code having specific format. Steps to create new rule and what fields are available in rule expression, are available at: Customizing workflows.