To perform the customization, you will require access to a Dynamics 365 module along with a System Customizer or higher role. An IDE or a JavaScript editor of your choice is also recommended. To test your OData queries, consider using the CRM REST Builder solution written by Microsoft MVP, Jason Lattimer. Also, consider a REST query tool to rapidly test your queries. Chrome's REST Console add-on is a good one.

Additionally, users will require the appropriate access to the relevant entities being queried.