Follow this guide if the Salesforce account does not appear in the account selector.
Have the manage billing permission in permission sets (more details in this Salesforce documentation).
To add the "Manage Billing" permission to a Salesforce user, follow these steps for a cohesive setup:
Create a new permission set
In Salesforce setup, search for Permission Sets.
Click on New Permission Set and provide a name (e.g. Billing Admin) and description for the permission set.
Save the new permission set.
Add manage billing permission
Within the newly created permission set, navigate to System.
Click on System Permissions and then select Edit.
Locate and check the Manage Billing option, then save your changes.
Assign the permission set to the user
After setting up the permission, go to the user’s profile for whom you want to grant this permission.
Under Permission Set Assignments, click on Edit Assignments.
Select the permission set you just created and save the assignments.
