CoursePress Pro will not activate

Dear support,

Today, I purchased the CoursePress Pro plugin through your site. However, after installing, when I try to activate the plugin, my Wordpress-site stops working, both the front-end and back-end.
The error that we get is (in Dutch):

"De pagina op http://www.fngsh.com werkt niet
http://www.fngsh.com kan dit verzoek momenteel niet verwerken.
HTTP ERROR 500"

Which translates to: "The page on http://www.fngsh.com does not work. http://www.fngsh.com cannot process this request at this moment. HTTP ERROR 500".

Luckily, I can reset this by removing or renaming the "coursepress" directory in the /plugins folder on the FTP site (using a separate FTP client).

I have tried installations both manually (uploading the unpacked /coursepress folder after downloading the ZIP file from your site) and automatically through the WPMU Dashboard plugin which also uses the FTP protocol to install the files. Both methods had the same unfortunate results.

Can you please help use to activate CoursePress?

Kind regards,

Robert de Bruin