Just add the line sv_scriptHookAllowed 1 to your server.cfg file generated by txAdmin, there are also links for more commands you can use
# This file is a minimal version of the default config file.
# This is NOT supposed to be enough for a fully running server.
# Please read the fivem documentation:
# https://docs.fivem.net/docs/server-manual/server-commands/
# https://docs.fivem.net/docs/server-manual/setting-up-a-server/