p.s. Just to make clear, the https://chirp.social system uses account addresses.

You create a group by registering on https://chirp.social. You join the group by following the group's account address. You post to the group by mentioning the group's account address.

More info about what account addresses are here: https://fedi.tips/how-to-use-mastodon-and-the-fediverse-basic-tips/#WhatsMyAccountsAddress

Every account on the Fediverse has a unique account address.

So for example to join the Art group on chirp.social you follow @art