Hi @VandanaRajput,
When you say you added NameCoach to your course, do you mean that you just enabled is in your course navigation options, or did you attempt to install the tool form the Apps page? As far as I know, NameCoach is a 3rd party tool which requires a paid license. My best advice is to let your local Canvas administration team (usually in the IT / eLearning / Digital Education areas) know you're experiencing an error with the integration and they'll hopefully be able to help. We have NameCoach at my institution as well and are not experiencing any issues with it right now.
I hope this helps a bit!
-Chris