An order, as shown in Rental Management for D365 Sales, can be created in D365 F&SCM:
Automatically when a rental quotation is confirmed, resulting in a rental order.
When a project rental quotation is transferred to a project, resulting in a project rental order.
Manually as rental order or project rental order.
For (project) rental orders and lines, a one-way synchronization is applied. So, you can edit a (project) rental order and its lines in D365 F&SCM only. If you edit a (project) rental order or line in D365 F&SCM, the changes are synchronized to the related order in Rental Management for D365 Sales.