The permissions listed here are the ones you need to explicitly enable. Some Salesforce permissions auto-enable others, so not every permission that gets enabled will be explicitly listed here.
View Setup and Configuration
Enables the integration to access the Salesforce setup configuration in order to create a custom field
View Roles and Role Hierarchy
Ensures the integration has the correct visibility context so the connection can successfully read records.
Manage Custom Permissions
Allows the integration to create and manage dedicated permissions to create a custom field.
Customize Application
Allows the integration to create and manage application setup, including custom fields.
API Enabled
All of the subscription creation and updates are done via API requests
Author Apex
Allows the creation of an Apex trigger to filter out the fields that are of interest
Manage Profiles and Permission Sets, Assign Permission Sets
These additional permissions are required because, before creating the custom checkbox field, our setup creates a dedicated permission set to manage field access and field-level security for that field.