Theme activation errors are usually related to the server configuration. Some hosting providers block all connections to remote servers (for security precautions). You might get errors like
cURL error 7.
It’s best to ask your hosting provider to either temporarily disable this filter when you’re registering the theme or you can whitelist the IPs on this list from CloudFlare. We use CloudFlare as our CDN of choice in front of our server so when your server is trying to connect to ours to verify the purchase, it will connect to any of the IPs from their network.
If you are unable to resolve the problem, please open a new private ticket and we will help you.