I don't get you request. You write that you can use it to upload and in the other part of the sentence you write that it does not work. Anyway, this is how it works:
On the server side you have to create API keys:
Admin --> API --> Generate Key with Read & Write Access
Note down the key (or copy) (e.g. something like this cl5f4e7bdce96dd and insert this into the App.
The cloudlog url must be written without http:// or https:// in the front, because this will be added according what you select in the dropdown menu.