Hold on a moment while we finish that action and refresh the page...

HI, I'm trying to install Appointments* on http://www.cdgranviamar.com and the message is "Hold on a moment while we finish that action and refresh the page..." and it's no working. I'm holding on for 3 days. Can you help me please?

I've tried to install another plugins and I could install many plugins, and I coludn`t install meny others.

What I have to do?