If an Availability Group contains two FCIs, how many quorums do I have?

To have an Availability Group, I must have a Windows Server Failover Cluster. All Windows Server Failover Clusters have the ability to form exactly one quorum. This clearly means that if I have two Failover Cluster Instances, I must have two quorums. But what happens if I make an Availability Group out of two Failover Cluster Instances? **Do I need to manage three quorums?** [The documentation](https://learn.microsoft.com/en-us/sql/database-engine/availability-groups/windows/failover-clustering-and-always-on-availability-groups-sql-server?view=sql-server-ver17#WSFC) certainly gives the impression that the Availability Group is subject to the vote of a quorum, but I don't know which quorum.