How does one set up multiple organizations under a single Okta account

I’m trying to figure out how to do multi-tenant / multi-org with Okta. Say for example I want to have a stage and production environment where the users are completely separate but the same usernames can exist in both environments with different passwords. Groups won’t work because the username has to be unique across groups in the same org. So how are people doing this?

We have an Org connected to our Pre Production user respository and an Org connected to Prod

Thanks. I assume is for enterprise accounts. I don’t appear to have access to that. I’m still using a developer account while I’m in the evaluation phase. Though I suppose I could just create multiple developer accounts for my non-prod environments.