If the design was posted here and you do not need any changes to it - it is OK to save and use the design without permission.
I am making a presumption but...
as designers we enjoy others getting the use of our designs and that is why we post them here. As long as you are using it for your own personal use, there is no need to ask permission.
This is not speaking for all designers but every time this question arises, we all seem to agree that asking permission is not necessary.
I just now saw it was for use in a new design - for that, yes, you should ask first. Sorry, I misunderstood.