The UI for registering for events is broken in the 3.x version. You may want to try one of the similar registration modules instead first.
RNG is an event management module for Drupal 8 created in the spirit of Entity Registration (Drupal 7) and Signup (Drupal 6). Users can create registrations for events, and event managers can manage these registrations.
See the quick start guide for setup instructions and basic configuration.
RNG 3.x
RNG 3.x is minimally maintained. The basics of the API and data models are functioning, but the UI for registering for events does not. Drupal 10 support is planned.
The difference with the 1.x version is that the entity type "event_type" has been renamed to "rng_event_type". This is to reduce the chance of naming conflicts with other modules.
At the moment there is an upgrade path for configuration entities, but not your data. If you are starting fresh, use the 3.x branch and come by the Slack #rng channel if you have any trouble. If you currently have event data in RNG 1.x, we would appreciate patches to migrate event data.
We are also bringing the issue queue back here to Drupal.org -- if there's something you don't see, please open an issue here!