To access Juxtaposition on your console, link a PNID to your console (assuming Nimbus is set to connect to Pretendo).
You can link a PNID by opening System Settings > Nintendo Network ID settings whilst connected to Pretendo in Nimbus. Then, you can link an existing PNID or make a new PNID.
Once you've entered your credentials or you've finished the setup process, you should now be signed in and you should be able to access Juxtaposition.
For further support with this error code or any associated error codes, please look for a solution or make a support post on the forum.