Send a mail to account@nuget.org with the owner display name on nuget.org, as well as any reserved prefixes you are requesting. If you are delegating prefix subsets to multiple owners, make sure you mention all owner display names and prefix subsets.
After the application is submitted, you are notified of acceptance or rejection (with the criteria that caused rejection). We may need to ask additional identifying questions to confirm owner identity.
ID prefix reservation application process
After the application is submitted, you are notified of acceptance or rejection (with the criteria that caused rejection). We may need to ask additional identifying questions to confirm owner identity.
https://learn.microsoft.com/en-us/nuget/nuget-org/id-prefix-reservation#id-prefix-reservation-application-process