Present perfect progressive is used when an action that started in the past continues even in the present. We use "have been + <verb+ing>" for "I, we, you, they" and related nouns. These sentences use "has been + <verb+ing> for "he, she, it" and related nouns. In addition to that, the verb used in "has/have/had been" structure is always used with "ing" as the action is supposed to be continuing.
This is used with actions that have started in the past, continued for a fixed period, and then ended in the past too. In these cases, we use “had been + <verb+ing>”.
This is used when an action would have been continuing from a more recent future time to a much distant future time. structure "will have been + <verb+ing>" is used with actions that started in the past and will continue till a given time in the future.