Does not work with BigBangWP theme?

I’m running BigbangWP theme and I cannot get the landing pages to use any of the page themes included in the plugin, it always uses my themes design.

I tried everything you mentioned to other people when they get a 404 error. Activated 2014 theme, updated wordpress, disabled all plugins, uninstalled and re-installed the plugin and went to permalinks. Still does the same thing. I can see at least 4 other mentions of this with the response “we’ve never seen that” .. so here’s another one. I’ll just use a different plugin as I’ve wasted too much time already watching videos and trying to get this plugin to work.

https://ww.wp.xz.cn/plugins/landing-pages/