You can claim your course certificate upon course completion. You would be able to use this certificate on your resume, Linkedin profile or your website.
It appears you have not spent sufficient time studying the course. You may go through these suggested lessons (again) to claim the certificate
SUGGESTED LESSONS:
Combine: Merge, Concat, and Zip
Challenge
Schedulers with Operators
Reactive Everything: Multicasting
Retry Operators
Why? If I completed everything