No you haven't. Get back to the 'Basic' mode and set the 'Network Type' to 'Custom: br0'. Set the 'Fixed IP address' field to your desired IP address. Be sure the IP address does not conflict with other static IP addresses on your network The WebUI port has to be 443. Http:// access is denied. You can only use https://.
Example:
If you don't know how to do this simple networking, then you should reconsider using ownCloud, especially if you want to access it outside your network. The ownCloud Docker itself is pretty secure, but you have to be careful mapping external ports to the internal network.