Error When Installing a CASE MERGE AppExchange App

I am trying to find a FREE product in AppExchange to address duplicate Cases in NPSP.I found 'Case Merge' which seems to do what we are trying to accomplish.

When I was trying to download, it hangs at the login screen which comes after 'Get it now'.

Thanks for your support.

Also, If there is any other AppExchange product you might have used for case Merge, please let me know.

Thank you!