Here is a script which lets you pick a ZIP file from your storage area, which is then downloaded by your device. After that, it reports the file size and MD5 checksum in the status columns. The action all happens at the bottom of the script.
Download the attached file to your system, then upload it to remot3.it:
If you are on Windows, editing this file in Notepad will cause issues because the line feeds are not compatible with your Pi Linux OS. We suggest you use a Linux compatible text editor for Windows such as Notepad++.
Next, upload the ZIP file as you did the script, but selecting "General Purpose Content" in the dialog.
Next, run the script and select the ZIP file you wish to transfer.