The data is from https://springernature.figshare.com/collections/Upper_limb_activity_of_twenty_myoelectric_prosthesis_users_and_twenty_healthy_anatomically_intact_adults_/4457855. Specifically, it is the ActiLife 1 second CSV files zipped from https://springernature.figshare.com/articles/dataset/1s_epoch_activity_count_data_stored_as_csv/7946168. It is simply repackaged so that individual files can be downloaded. Please cite the respective data there.