Imo you should definitely tell your client to create an account.
Then on your side in Botpress you create a workspace with you and the client.
This seems essential to me since the client pays you to create a bot for them, but what if you decide to not work with them anymore ? The bot is still owned by the client.
Also, you can see this with your client, but it would seem logical that the client pays their own Botpress subscription.