can't see posts text in back end

Version 1.8.3 of the events plugin. When trying to write/edit a post, the menu with the visual editor stuff, or the b/i/link/other things with HTML editor doesn’t appear. And the text in the post editing box is all white on a white background (can only see if it’s highlighted). Unless the user also has the “manage_options” capability. Which I don’t actually want to give all the authors. So, any ideas for what’s going on here?

https://www.ads-software.com/extend/plugins/all-in-one-event-calendar/