Some blog owners are becoming confused by the AdSense activation process, and are applying directly to AdSense. If you apply directly to AdSense, you will be applying for an AdSense For Content account. AdSense For Content requires a properly qualified top level domain website. If you have a fully qualified top level domain website - or a Blogger blog already published to a custom domain, again, fully qualified - you can add a Blogger blog published to BlogSpot, as an additional ad host. If, like many Blogger blog owners, your blog is your first step in Internet activity, you cannot accomplish anything by applying directly to AdSense.
What Blogger won't tell you