How to set up a subdomain for short links (List of Registrars)
Follow the detailed instructions on how to register a subdomain and add it to Short.io. Choose a guide depending on your domain registrar.
Or If your registrar is not on the above list, consider the following article:
https://help.short.io/en/articles/9690708-general-domain-setup-instructions
In case of any questions, feel free to contact the Short.io support.