Testcafe and Browserstack - Unable to find browser

I run want to run tests on a jenkins server. Locally the same code and credentials work.

When i start the test-runner on the test-server i get: Unable to find the browser. "browserstack:chrome" is not a browser alias or path to an executable file.

Before running the code the browserstack application is downloaded and started as described here: https://janmolak.com/jenkins-2-0-pipelines-and-browserstack-bd5a4ed3010d

I also tried this: '''./node_modules/.bin/testcafe -b browserstack''' which also does work locally but fails on the jenkins server.

What could be the reason or how can i get more info about what happens?