Create a new membership associating a user with either a company or an organisation node. Memberships define the relationship between users and the entities they can access within your organisation structure.

The membership must include a relationship to either a company or an organisation_node, but not both.

🔒 External clients call this endpoint with an OAC (Organisation Access Credentials — ⚠️ Beta) access token carrying the users:write scope.

ℹ️ Each user can only have one membership per company or organisation node. Attempting to create a duplicate membership will result in an error. You can configure the user's role (admin, developer, viewer, etc.) and notification preferences when creating the membership.

ℹ️ Set meta.with_invitation to true to have Fintecture send an invitation email to the user.