The Tersus server should be in a folder accessible to the user running tomcat, not necessarily as a sub folder of the tomcat root folder.
If you're unsure, I suggest you follow the instructions found in http://www.tersus.com/#Id=242, using the folder names and locations specified there.
Note that paths are specified in the documentation using Linux/Mac notation, with forward slashes [/] used as folder separators. If you're accustomed to, and installing on Windows, just convert these to backward slashes [\], when creating or verifying paths in the file system.
If you've tried following the instructions but still having trouble figuring it out, you're welcome to post more details, attaching the context file of the application you're trying to deploy and the log files of tomcat (found in the logs subfolder of tomcat).
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