Yes, you’d need to change the launch link. See this post &thread.
This URL based on information there gets close, I think:
https://mybinder.org/v2/gh/textmining-infopros/dashboard/main?urlpath=%2Fedit%2Fflexdashboard_R.Rmd
However, I’m unsure what “Jupyter Notebook” style is for this type of file. When I click on it in the Jupyter notebook classic interface, it wants to edit it, and so I tried linking to that.