SaveTo.Downloader is System tool that is open source under the CDDL-1.0 license.
A companion app to SavingTo (https://www.openapk.net/saveto%A6/xyz.myachin.saveto/). It has no storage permissions and can only download files and save them internally. The task of this application is to tell the SaveTo that the file for it is downloaded, because the SaveTo itself cannot download anything. And vice versa, the Downloader cannot read anything from or write to the file system. Thus, even without reading the source code, it is obvious that this application is not able to steal data from your device.