It would appear for some users the park domain function is not correctly working.
In the meantime users can use the point domain option (better anyway for DNS management) in conjunction with CloudFlare if you so wish.
Website Creation Unavailable
We are aware that free plan users are unable to create any more new websites / new signups are unable to make a site. Our team is actively working on resolving this issue, and we appreciate your patience. No ETA for Resolution:
At this time, we do not have an estimated time for when the issue will be resolved.
Users can use Hostinger Premium without issue in the meantime or seek alternative free hosting
https://www.hostinger.com/special/000webhost?utm_source=000webhost&utm_medium=frontend&utm_campaign=moderator
Thank you for your patience.