On CSO go to :   Resources / Site Templates

Run the Wizard and Provide:

NG-FW capability:

1- name and description of the template. example sdwan-site-template, srx-ems-stite-template

2- select the capabilities: SD-WAN, NG-FW, LAN

3- Address

4- time zone ( NTP server)

SD-WAN Capability:

select the type of device: SRX, NFX150 or NFX250

BYOB, single or dual,...

number of uplink 

number of subnet toward the LAN ( DHCP or not )

. . .