You can override quorumDenominator to get a custom proportion. The default value is 100 but with the denominator as 1000, your requirement can be easily fulfilled.
OZ Wizard
For me, the Wizard just bugs out with an error in the console if I enter a fraction and then I can even click both the radio buttons.
In general, all crypto is in integers. It will never like 0.1, it needs some kind of divisor to keep everything in integers. So 0.1 100ths is not copacetic, but 1 1000ths is. That's why you need to update the denominator per @atharvashukla
I had posted an Issue on the Wizard Repository on Github. (Link to the issue). And it was closed today with an update to the Wizard. It can now handle decimal values for the quorum!