September 5th at 12pm EST. It's important to remember that Kickstarter only charges you after the campaign has ended and has been completely funded. That means that although you don't have the money ready today, as long you have it by September 5th at noon EST then you can make a pledge in advance.
If you are interested in purchasing the "Collaboration Package", we have until September 5, 2018 to complete it (one year after the campaign ends). It doesn't necessarily have to be released by then but it will be written, produced or recorded within that time frame.
Don't see the answer to your question? Ask the project creator directly.