I follow the documentation and created an application (under " LoRa Network Server").
According to the documentation (section 3.4.3 Applications in RAK_LoRaWAN_Industrial_Gateway_Configuration_Guide_V1.4) there should be two tabs in this screen: Devices and Application Configuration.
The Devices tab is missing.
p.s I am running firmware: 1.1.0045_Release_r176.