Hello!
It appears that you are looking to link a Canvas Badges / Canvas Credentials issuer to a Canvas LMS course after installing the LTI at the course level? If so, then the LTI needs to know which issuer(s) you are an owner of (and can therefore link to the course), and this is why it asks for your email address.
If this is a different use case, please feel free to share any additional information that might allow us to better understand the challenge and make targetted recommendations.
