Pre-sale issues

Hello, I am interested in buying this plugin however there are some technical issues in the free version that is making me hesitant, so the issue is that whenever I create a new product builder and try it the first step says Please enter a valid quantity for this product, I don’t have a minimum qty or anything that could prevent the selection I enabled the qty feature and I tried to select but this time does not do anything at all no selection is made , please solve this issue so we can upgrade