Users and privileges.

The webserver needs a valid user to perform its actions. This can be the loged in user in the dashboard, or a toke defined user either set as an anonimous token or provided by a script.
In addition, the server node needs some privileges to be able to access its own data.

User privileges.

In addition to the usual privileges the user needs the privilege to read and write on web.

Open the serve→Domain configuration in the menu. The domain configuration will let you configure your users privileges.

Without this, no data will be returned on web access.

Node privileges.

In addition to user privileges, the node needs some privileges to be allowed to return data.

To get full multi server instance access the node needs.
Read and execute on all servers and read write and execute on all instances.

Open the serve→Domain configuration in the menu. The domain configuration will let you configure your nodes privileges.

Without this, the coresponding functionality will be missing.