You have encountered this error because as a joint user, you do not have the necessary access rights to change settings related to data sharing for the BMW vehicle.
Solution
To resolve this issue, you need to ensure that you are the main user of the vehicle. Only the main user has the authority to modify data sharing settings and add new cars.
This can be done by getting in touch by the BMW Connected Drive support, if the user management in the MyBMW App does not allow to change you to the Primary user.
The list of current users and roles is available both in the vehicle and in the MyBMW App so that the user can always request Primary handover from the current primary user.
If you are unable to change the user status or encounter any issues, please contact BMW Customer Support for assistance.