I have a rather large folder in my cloud storage (OneDrive, Google Drive and Dropbox) It is 8GB large with 3-4 files. It is a backup of important folders from a computer that was long ago replaced and destroyed. I want to download this large folder and put it on a Thumb Drive then delete it from the cloud. Obviously clearing up some storage space.

So my concern is possible corruption in the process between cloud and Thumb Drive. Is there a way that I can create a Checksum for the cloud folder (or separate files in the folder) that can be used to check the integrity of the folder/files in the Thumb Drive before deleting them in the cloud?

I have searched but all I can find are ways to use an existing checksum to check the integrity of a downloaded file. Nothing on how to actually create that checksum on the file before downloading.