Recordkeeping Mode is a setting located within each individual Project. You can find it by selecting a Project, then selecting Project Settings from the left-hand project menu, then it is a checkbox option at the bottom of the "Basics" tab of the Project Settings screen.
Recordkeeping Mode governs whether Rivur will (Box = UNCHECKED) send emails to connected Vendors and allow Vendor access or will not (Box = CHECKED) allow Vendors to interact with this Project.
Recordkeeping Mode is set at the Project so that you can control which Projects a connected Vendor can see. You can choose to connect with a Vendor on one project and not another and this control is how you delegate that access.
When a new project is created, Recordkeeping Mode is checked by Default (i.e. collaboration is disabled by default). You will need to uncheck this box in order to allow Vendor access.