Need help with registering opportunity in partner portal to enable signing NDA (Non Disclosure Agreement) between our clients & Celonis.

We are planning to work with one of our customers to show case Celonis dashboards that we have created.  We need to get a NDA signed between our customer and Celonis, after which we can use their data for Celonis Dashboards. Upon reaching out to our Partner Manager, he provided us with the process that firstly involved registering the opportunity in partner portal (https://www.celopeers.com/s/partner-register-opportunity) and provide the customer name and contact person. When we tried registering we are getting the attached error, can you guide us on how to register the customer in the portal ?