Udemy sends out a confirmation email whenever you enroll in a course. So, as an initial step, please ensure that you are logged into the same email account that is registered to your Udemy account, and that you received an enrollment confirmation email for the course. Be sure to check your Junk mail folder if you don’t see the enrollment confirmation email in your inbox.
If you don’t see a confirmation email, this could indicate that you purchased the course while logged into Udemy with a different email address (see below), or that the purchase was not completed. Udemy also advises checking your banking information or your PayPal account to verify the purchase was processed.