This is a new install. when clicking on “EXTEND” and then “+Install New Module”, this error message is displayed:
Your server does not support installing modules and themes from this interface. Instead, install modules and themes by uploading them directly to the server, as documented in Extending Drupal 8.
Before I installed this new version, there used to be a field to enter the URL of the new module. Drupal would then fetch and install the module for me. That field is no longer visible.