Thanks for providing that. So the issue is that there is a formatting problem with your certificate which is what the server responded with. That's why after the call it's not present on the cluster.
It looks like your certificate string is missing line breaks encoded in the string. Try adding a \n to the end of each line of the string.
This example script might help you: https://github.com/NetApp/ontap-rest-python/blob/master/examples/python_client_library/cert_auth.py
It goes through a complete workflow of creating, installing, and using certificate authentication.
"not working" is not giving me enough information to give more specific help.
You might want to enable debug logging on your script so that you can verify the HTTP request and responses that are sent/received. There might be additional information there that will help you. Here are details about how to do that: https://library.netapp.com/ecmdocs/ECMLP2879970/html/index.html#log_all_api_calls-flag