Oh wait…
I think this is an old error: There never was made a spigot version for 1.8.9 (https://www.spigotmc.org/threads/minecraft-1-8-9.107939/). Therefore when you press build, it do not build it.
See also this older thread tha tdiscuss the same issue you are having: Issue starting Spigot server
Try 1.8.8 or 1.9.0 instead. There where only minor client changes between 1.8.8 and 1.8.9, so the 1.8.9 clients happily connected to 1.8.8 servers.
Sorry for not catching this earlier 