I can't authenticate the Autodesk license for a educational institution.

The Autodesk license for a educational institution is authenticated through a student identification.

However, you need the student ID or transcript for an examination and the authentication is not sometimes done by a student identification.
※It has been reported the examples, the reauthentication after more than a year has passed since the first time and the authentication by a student identification failed.
You can't use the education free software in this state.

In this case, please recreate your Autodesk account.

The procedure is the following.

1. Create an alias address refer to "how to create the email address(alias) from a G-mail address".
   ex) aa00000+autodesk@shibaura-it.ac.jp
2. Sign in using your until now Autodesk account.
3. Open the screen of account management,and change the address to the alias one is maked by 1.
4. As well, please chnage the username.
   ex) aa00000AUTOD
   
5. Change the browser done the above procedure to the other one.
6. Make a new account using the old address.
7. Do a licence activation with a new account.

You can do licence activation not to submit the documents because the licence activation with a new account can do SSO.

Please the following page about the AUtodesk.
http://download.sic.shibaura-it.ac.jp/Autodesk/index.html