Unfortunately due to security settings I won't be able to access your site to see this issue in action, your site is flagged as a site containing either malicious or adult content.
Make sure you are setting up physical products, not digital products. The product owner will receive emails including shipping addresses to the email address associated with their forum account.
You also need to set up shipping zones and shipping methods, and associate the created shipping zones with your products when setting them up.
Once you have done that, the system will ask users for shipping addresses when purchasing your products, as long as the cost of the product is above 0.