Wireless Access

We currently have a few Aruba AP-518 access points. We want to create a mesh wifi between a few offices (1 on ground floor and 3 on upper level). Our fibre incoming network comes in at ground floor and connects to a Gigabit POE switch. The 1st Aruba will then connect to this switch and act as the mesh "controller". I then want to setup the access points to see this mesh AP and connect to them on the 2.4ghz radio and then use the 5ghz radio to broadcast the SSID for end users to connect up. Is this possible and if yes, anyone got any guides/tutorials? We are not using Aruba central, we use the Arubas as standalone using their virtual controllers. Any help/guidance would be much appreciated. Thank you.

You're looking for the mesh feature.  Instant will only use the 5 GHz radio for mesh.

https://www.arubanetworks.com/techdocs/Instant_8.12.0_WebHelp/Content/instant-ug/mesh-network/mesh-network.htm

There should be some other guides available for mesh if the documentation is insufficient.