I fixed an old script from thomersch that downloads mapillary sequences to work with the new API, and hopefully you find it useful.
Once you’ve installed the program, put it in a folder where you want the images to be.
When you double click on it, it will ask you for your client id and the sequence id.
You can find the sequence key by viewing an image on the mapillary website, and clicking advanced in the image options button
You can get a client id by creating an application here
Enter this info into the window, and you will see the status of the download and how many images are in the sequence.
Once the download finishes, the window will close and the downloaded sequence will be in the downloads folder where the program was installed.
If you have any issues with this tool, please let me know and I will try my best to help you.