it is completely up to you and depends absolutely on what you want. If you wish you can have there the same URL as Main site URL or something else if you need/want to have there something else. You should also not forget that the Declined site URL is used only in case you use Standard/redirect links http://support.qualityunit.com/991920-Standard-links-redirect-links
and Mod_rewrite links. With New Style and Anchor links the software doesn't affect the destination URL in any way.