An important design goal of ProAuth is to support multi-tenancy all over the product and its functionality. A tenant is a customer / subsidiary / business unit using the application which authenticates through ProAuth. Often those entities have specific needs like special configurations, different federation settings or different requirements for second factors or simply just want to see their logo on the login screen. An authentication / authorization process always happens within a tenant configuration and therefore can be fully customized.
Technically, each tenant configuration spins up an authentication pipeline, so the authentication process is always specific for a tenant.