Unable to find Gen Application Key for my Device

I am trying to implement FUOTA with the chirpstack-fuota-server.
I am working with this example .
This example needs the parameter GenAppKey and I can’t find this parameter for my device.
I saw that this parameter was in Devices/myDevice/keys(otaa) under the field : Gen Application Key.
But in this tab, I only have the Application Key. (See screenshot)

Is this parameter still available in the application server or is there a new way to acess to the devices with current version?
We are using following versions for our services :
chirpstack-application-server 3.15.0
chirpstack-network-server 3.13.0
chirpstack-gateway-bridge 3.11.0
chirpstack-fuota-server 3.0.0-test.3
Thank you for your kind help

Does your device support FUOTA?

Hello brocaar,
My device is going to support FUOTA, I am currently implementing it.

In that case, you would have to implement the configuration of this key as well as part of your FUOTA implementation. The important thing is that the same value is configured at both sides (device and application).

Sorry for late answer,
Regarding your message, I would like to know where do I need to set the key configuration in the application ?