WordPress Automatic Plugin Sitemap not working

I recently purchased this plugin, based on the capability of the plugin as advertised on the link below:

We have followed all the instructions, but it still dont work.
We have contacted as per the instructions the author below, but still waiting for a response.

https://deandev.com/support?envato_item_id=1904470&ticket=19476&accesskey=bhsvAnpo4mKC

The author should reply you within 1-2 working days. You need to be patient a little more

HI there. I had a brief reply to the ticket, and commented, but now 6 days later and still no response.

I also offered to pay for support as I want this to work, and if I get this to work to purchase another license of this plugin for a different site.

I don’t have much to say but I can offer paid support if you’re interested in

Me and my team can provide you with our top notch services and solutions so if you are really interested then please drop me an email at my envato profile