Easy Digital Downloads Problem

Hello, I am trying to use the Easy Digital Downloads plugin and I have problems which is shown on these pictures I’ve attached.

I contacted them about it and I got the this message

“Hi, Zoltan. It’s hard to say what’s going on at the moment because I don’t quite understand how your site is set up and what plugins you’re using. The unwanted text on the page is happening because of the invalid HTML in your markup. It’s visible there in your screenshot. However, I don’t recognize that as our HTML. It appears to be coming directly from your theme. So you will want to temporarily switch themes and see if it’s still there. If not, it’s a theme issue.

As for the language issue, what plugin are you using to control the language? Is this a multi-language site?” (I do not have one)

For translating I use the WPML plugin.

According to their advice I’ve tried on other themes like the Twenty-Fifteen theme. It works fine everywhere except here.

Please advice me what to do to fix these issues?

Best regards,

Zoltan