Looks like you have not entered the credentials in a correct format. Please enter the credenatils in correct format as suggested in the help text.
Please put the Subdomain carefully.
Your subdomain is the name you would access your program (https://subdomain.heightsplatform.com) at if you were not using a custom domain. If your program is located at "course.heightsplatform.com" then your subdomain would be "course".