I don't use this module but have had a quick look into it. It literally says how to change this in the instructions...
Check line 62 of the ops_scheduleform.tpl
But does it work? I wouldn't trust Dreamweaver, it's super old, and if it's giving you an error on that line, it means it doesn't know how to interpret namespaces. Use something like Atom or Visual Studio Code with PHP plugins.