Cannot install new plugins

I’ve been having this problem for about a week.

I have made no changes to server or the website: nitrorigging.com

When I try to add a new plugin here is the message I get:

“An unexpected error occurred. Something may be wrong with WordPress.org or this server’s configuration. If you continue to have problems, please try the support forums.”

So I’m here at the support forums!

Any ideas?

Thanks!