According to the Salesforce Revenue Cloud CPQ documentation, users need to have the Create, Read, Edit, and Delete permissions on the Quote object in order to create and manage quotes. If users do not have the proper accessto the Quote object, they will encounter errors when trying to create quotes, even if the quotes are set as primary by default. This is because the primary quote field is a lookup field that references the Quote object, and users need to have access to the referenced object in order to populate the lookup field. Therefore, the most likely cause ofthe issue is that the users did not have the proper access to the Quote object in the production environment, and this was not detected in the sandbox environment because the users had different permissions or profiles there.Reference:

https://help.salesforce.com/s/articleView?id=000316738&language=en_US&type=1

https://help.salesforce.com/s/articleView?id=000381216&language=no&type=1

In Salesforce CPQ, ensuring that users have the proper access to the Quote object is crucialfor the smooth creation and management of quotes. The issue reported by users in the production environment, where errors occurred upon trying to create quotes for the first time, likely stemmed from insufficient permissions on the Quote object. In CPQ, setting a new quote as 'primary' at the time of creation is a common practice to streamline the quoting process. However, if users lack the necessary permissions on the Quote object, they would encounter errors when attempting to create or modify quotes. It's important to note that in Salesforce CPQ, orders must be created from a primary quote, and once an order is created from a primary quote, the quote cannot be edited. This indicates that the underlying issue is related to access permissions on the Quote object, rather than post-installation scripts, access to the Opportunity Product object, or access to the Quote Line object.