Can't join events

New to the platform. Signed up after free trial finished. Tried to join a number of events via the app and the Companion Android app (always before they start). When riding the “join event” button never appears (I have only read about this online). There is also never anyone on the course when I am riding.

Any ideas?

Could you tell us which platform you are using for Zwift (Windows, mac, iOS, tvOS)?
Are you always stuck in the same world every day or does it change?

Mac.

World changes. London recently but have been in other courses before.

If you can log in but always are alone on the roads it is most likely because some of the network traffic between your computer and Zwift servers is blocked (e.g. by your firewall).

The troubleshooting tips here can help you:

https://support.zwift.com/en_us/"check-your-internet-connection"-error-(cycling)-BkWrZC1WSQ

but essentially you have to make sure that your firewall allows TCP traffic in both directions at port 80 and 443, incoming UPD traffic at port 3022, and incoming TCP traffic at port 3023.

Otherwise, go to support.zwift.com and raise a support ticket if this does not help you.