There are a couple of reasons why Spotify may have denied your claim for access to your artist page.
Do you have a live release that was delivered by Record Union?
It isn't possible to get instant access to your page until you have a release live on their platform delivered by us.
Has your first release gone live in the last 2-3 days?
Spotify 4 Artists is actually a different platform/app to the regular Spotify, so it can take a few days for the details of a new artist page to go from regular Spotify to the Artist portal, even if the release is live. Therefore you'll just need to keep trying and eventually Spotify's systems will catch up.
Are you trying to claim your artist page before your first release goes live?
Contact the support team with the UPC for your first release.
Once your release has been reviewed and delivered by the content team (usually within 5-8 business days), we can send you your new Spotify URI. As the instant access feature is only available if the profile is live and has a release that has gone live on it, you will need to claim your page at https://artists.spotify.com/ and click 'skip instant access' when prompted.
Please note that it can take up to a week for Spotify to grant you access to your profile in this way, and if you want to pitch a song to Spotify's playlist editors, they recommend that this is done at least a week before the release is due to go live.