Team Ulysses' Ulx doesn't include a setspawn command. (
/index.php/topic,3254.0.html )
If you have an addon that adds a set spawn command for ULX, you should ask in that appropriate release thread for the addon that does.
I took the 3 seconds to use the search function within the forum community releases section for the word "setspawn".
This link finds it in 3 different release topics. /index.php?action=search2;params=eJwtzDEOgCAQRNG72Nhq4XkILJOgQZYsKDHh8C7G7s8rxvrbJoLvc1_61J2MWjfNErgZ4jNHVCgOutwBqoZTfH5hqVqCiO_nJ-N3UfYoNARWKOguqCXbll6Jai5x
If you're not using those releases, then you may wish to research further and find your addon's support method.