Could not activate Visual Composer plugin

Hi,
I’ve purchased Highend theme last week for some project, but I have an issue to activate required plugin Visual Composer after re installing wordpress. Every time I tried it fires an error “You do not have sufficient permissions to access this page”. Can I get help with this?
I would like to understand what happens because I probably need to re install wordpress again in different folder.

Purchase Date: 2014-07-27 05:02:05
Transaction ID: #1578141

Thanks,
Jovo