Thank you for your reply.
I'm not using a KMS server.
I entered the product key online and installed the activated software offline on windows Server. The PC can be activated in this way.
I launched the excel installer on the server, downloaded it, and tried to activated by phone. However, I got an error message that the key input was wrong and failed to get the confirmation ID.
I'm worried that it will be transmitted in poor English, but I would appreciate it if you could answer.