If you get a message like this "Warning: No Payment options are available" when you try to checkout then check these points:
- Have you enabled at least one payment method
- Have you set the right Geo-zone for the payment methods you have enabled
- Have you setup the Geo-Zones correctly.
If, you are not really sure what a Geo-Zone is then select 'All zones' in the payment module configuration.
This link will help shed some light on Geo-Zones in OpenCart: