About AutoCAD "license not available" warning

Since the message "license cannot be used" is output,
It is presumed that Revit was installed from the on-campus download server.

In this case, the possible causes of the symptoms are:
Not connected to SRAS-VPN,
Alternatively, the borrowed license may have expired.
*Although communication with the license server may be blocked for some reason,

In the latter case, it may be necessary to reinstall the software.
It seems that there is a description on the AutoDesk page on how to return / borrow the license, so
I hope you will find out for yourself.

For reinstallation, please see the page below.
Please refer to this.

http://download.sic.shibaura-it.ac.jp/Autodesk/index.html