I wish the developer provided at least a little support for this. There also seems to be a lot of unawnsered support questions on their forum with some people waiting for over a month with no reply.
Thanks for purchasing this extension. At Joomla Tag we take customer support very seriously and every issue is important to us. We have sold dozens of this extension with only 3 customers posting issues on our forum for this product. The original release of this product had the 500 error for joomla 1.6/1.7 but we fixed this issue about week ago and uploaded the new files. Please send us an email firstname.lastname@example.org and we guarantee a prompt response to your issue