You should port FGT config instead of Juniper's at this forum. If you want to ask about Juniper config you should go to their communities at "Elevate" https://community.juniper.net/home
First, FGT doesn't have concept of "native vlan" because it's NOT a L2 switch or L2/L3 switch-router. So the untagged VLAN 200 on the Juniper side connects to the physical/parent/non-tagged interface on the FGT. You need to configure L3 for this at the parent, say 'port 1' interface. Then all the other VLAN subinterfaces under the parent 'port 1' interface. You obviously need to create a set of policies to allow access between specific combinations of VLANs.
