If your domain was suspended by the registrar, you should be able to get this resolved with them and point your domain to InfinityFree’s nameservers afterwards.
If it’s redirecting to suspendeddomain.org though, this is expected behavior when your domain points to the nameservers without having been added to an account:
In this case, this means that your domain is indeed pointing to the nameservers, and you should be able to add it. If this is the case, and you’re still facing the issue, can you share your domain name?