Contrast is a commercial tool. If you are interested in running Contrast on the Benchmark, you'll have to get a license for it from the vendor just like you would for any commercial tool. Once you have it, you need to place the contrast.jar file in this directory in order to run the Benchmark with Contrast using one of the runBenchmark_wContrast scripts, and then crawl the Benchmark to generate scan results with one of the runCrawler scripts.

See the Tool Scanning Tips page at OWASP (https://www.owasp.org/index.php/Benchmark#tab=Tool_Scanning_Tips) for the latest instructions on how to scan the Benchmark with any vulnerability detection tool, including Contrast.
