If I face this error, I would check whether the jar file is located under the mentioned directory and that the path in the command line is valid. Also, I would re-check the command used to install the update,
./jre/bin/java -jar <path to the JAR file of the update> <DENODO_HOME> -c
.\jre\bin\java.exe -jar <path to the JAR file of the update> <DENODO_HOME> -c
For your scenario, you have to add the '-jar' in the command used to install the update denodo-v80-update-202107152200 in your Denodo Platform installation.
You could take a look at the [**Installing an Update or Hotfix from the Command Line**](https://community.denodo.com/docs/html/browse/latest/en/platform/installation/installing_updates_and_hotfixes/installing_updates_and_hotfixes#installing-an-update-or-hotfix-from-the-command-line) section of Denodo Platform Installation Guide for more information.
Hope this helps!