SQL Server AlwaysOn

I am trying to implement SQL Server AlwaysOn.

Architecture :

3 nodes:
2 Nodes SQL Server Cluster -> with quorum
1 Node is SQL Server Stand Alone

My question is how i create the shared folder quorum for alwaysOn. Is it Mandatory we need a shared folder quorum?

I'm confused on your setup. Are you going to have an Availability Group on top of the SQL Server Failover Cluster?

You have an odd number of nodes, so you can use node majority for your quorum.

To make quorum changes, it's done in Failover Cluster Manager and not within SQL Server.

If by standalone you are looking at something like a reporting system - using read-only replicas from an availability group - then you may want to setup your cluster with a quorum drive. No need to use a shared folder - use a disk quorum in that configuration.

You also want to make sure you patch the servers so you can set the node weight on the standalone to 0 so it won't have a vote in the quorum.

Essentially, you will have a 2-node FCI cluster with a replica node hosting your reporting instance. You don't want the reporting instance to affect the cluster quorum or cluster health.