get https://rls.congacloud.com/api/sign/v1/cs-account/accessibleaccounts
Sub-accounts enable an organization to create child accounts within its
master account. For example, an organization might want to create child accounts on the basis of its departments,
geographical locations, or lines of business. Accounts can be created on three levels (parent > child > grandchild),
enabling an organization to manage many account types under its master account.