When logged in to your account, use the secondary menu to navigate to the Certificates page.
Usually this is because one or more of course videos/lessons in the course have not been fully watched, therefore, the course has not been completed. When one is logged in and going through the course the site software keeps track of how much of each video has been watched. This information is stored in the account and will mark the video lesson completed when the video has been fully watched. One thing that can be a little confusing is that a video or lesson may be marked as "viewed" in the course lesson list but this does NOT mean that the lesson has been completed. Each video lesson must be fully watched from beginning to the end and each quiz must be passed with a score of 70 percent for the certificate to be issued. Once the course is completed the certificate will appear on the certificate page.
One rare instance that might occur is that the Course Introduction video/lesson may not have been logged as completed in the account. Each courses introduction video/lesson is freely available to the public, which means that one does not have to be logged in to watch the introduction video/lesson. If an individual watches the introduction and then gets a subscription to the course, the introdcution video would need to be watched again, while logged in, so that the introdcution lesson could be logged as completed for the certificate to be issued. Watching the Introduction when not logged in and subscribed to the course may cause that lesson to be marked as "viewed" but will not be marked as completed for the course and a certificate will not be issued until the introduction video/lesson is watched while logged into the account.