Invalid token or (May be Session Expire)

I installed and tested Vquiz succesfully on my live site. It worked fine in the first session (Chrome). On subsequent sessions (Firefox and IE) it gave me errors though:

Invalid token or (May be Session Expire)

See: hielspoorinfo.nl/quizzes/hielspoor/doe-d...r-test-5-vragen/play

Earlier I tested this in a local dev test and it worked fine there.
See attachment

Hi Simon,
As the error message suggest, It's an issue with session expiry. You just need to refresh your page to make it work again.

I tried refreshing, this does not help, also if I clear my browsing history. Also I tested it on another browser where I had not used the whole site at all. It immediately gave me this error, and it keeps giving me the same error, also after refreshing / clearing browser history.

Please send us your back end FTP login credentials via Contact Us form, We'll look into it.

I sent the credentials

The issue is corrected, Please download the latest package after logging into your account. After logging int you'll see a My Orders section at the top right corner.