Hey thalaivi ,
Nick here from Shopify.
You'll only be able to use one of those conditions, not both. You can either offer a percentile off, or a fixed value off the price, but not both. I'd suggest going with the flat amount off, as that will mean you will be discounting less ultimately.
In the above image, you can see the control noted in the discount creation panel that restricts the use of the code to one per email or customer :)
Hope this helps!