I checked the page and the needed ressourses for the plugin are loaded, but the function to generate QR Code images is not automatically running.
When I execute it manually on your page, the QR Code image displays well.
It seems to be a conflict with your theme ‘Customizr’ which have a JavaScript error:
“setupDomListeners : dom element should be an existing dom element [object Object]” at 1:46859 in themes/customizr/assets/front/js/tc-scripts.min.js?ver=4.4.17
I tried to reproduce the error with the theme, but there is no error on my version and all works well. It may be a problem with your theme configuration and/or another plugin conflict that create this error.
You should check this issue from the theme with the ‘customizr’ theme support to solve this part of the problem.
In regards to have the QR Code on a restricted page for membrers, there is no problem all content in a private page is not visible from public side.
Thank you, best regards.