Fatal Error when trying to activate plugin

I am looking for an easy plugin to display PDF files for a club website – yet: Flowpaper apparently conflicts with my member directory plugin (which is a function just as essential to me and the members as viewing newsletters).
The attempts to activate quits with this message:

Plugin could not be activated because it triggered a fatal error.

Fatal error: Cannot redeclare endsWith() (previously declared in /home/baylands/baylands.org/web/wp-content/plugins/dynamic-user-directory/includes/core.php:3209) in /home/baylands/baylands.org/web/wp-content/plugins/flowpaper-lite-pdf-flipbook/flowpaper.php on line 238

How can I avoid this from happening, can you make a fix available?

The page I need help with: [log in to see the link]