There is an extensive user guide built-in to the software. It can be accessed on the Help tab of the Settings page, or in a floating window by pressing F12 at any time. There is also a shortcut on the Windows Start Menu to the help that will open it in your default browser.
You can always assign point values as prizes. For example, your first place prize could be 50% of the pot, and also award 10 points. If you only have prizes for, say, the top 3 finishers, but want to award points down through 7th place, you can create prizes for places 4 through 7 that have a points value only.
If your points distribution isn't that complicated, I'd go with the formula, since it's a one-shot that will award points to everyone who participates (including 0 points for those finishing beyond a specific rank, if you choose). It really isn't that hard, and someone here (myself included) can help.
I myself have never run a double-elimination style tournament. I'm certain there are those among us that have and can offer some pointers. Without any further explanation of your tournament, a double-elimination tournament sounds to me like a tournament in which every player gets 1 free (zero cost) rebuy.