An error page prevents users to procceed donation

Hello,
I have installed Joom Donation in my customer's website and I have also created a form.

Website: www.bikersforpeace.org

So, I've placed a donation module in the Homepage. The problem is that everytime someone tries to make a donation, when he place the amount and push the "Donate Now" button, an error page is displayed with the message "...the location you are trying to reach is not safe....you'd better leave...." etc. etc.
A message like this is displayed on all browsers (i.e., mozilla, chrome).



What should I do in order to fix this?
Do I need an ssl certificate in order to work?
Or is something else?

Thank you in advance,

Apos

Ok, I checked again the settings in the Configuration and it seems that I had the "Activate HTTPS" enabled.
As I haven't any SSL in my website right now, I disabled it, so now it is working.

Yes. If you don't have SSL certificate available for your site, you will need to set Activate Https config option to No. Glad you figured it out

Tuan