Config issue

[Masterjacker17]

Hello sir, I am fairly new to computer language but this looked fun and that's why want to try it out.
I am having 2 problems.

1. How do I change the api key,secret and auth url..how do i get my own auth url.? I have my own key and secret but how do i generate authurl. I have uploaded a screenshot. is it the right way of doing it?

2. getting error on few files stating Error: Size "Original" not available. how to change size?.

I downloaded few images with the default setting and it downloaded fine but only downloaded public files.on few of them it had size errors.

Please sir, I need your help on this one.