If you want to regenerate the Cloud Formation template to configure your AWS access, you can follow the steps below.
First, navigate to the vendor credentials page
*note the credential page requires admin permissions to access
On the credentials page, find the account you want to regenerate the CF template for. Then hover your cursor over the "..." icon next to the details button.
This will give you 4 additional options. Using the pencil icon will pop out a left side menu.
Here you will enter the S3 bucket name (if it is a payer account) and click the "generate template" button to receive a download of your CF template.