You might be saving the decoded binary data as ASCII-HEX file. Use CyberChef(https://gchq.github.io/CyberChef/ ) to decode Base64 and then download(save icon on output window) the file as binary.
Very satisfying. If you have trouble, look for a book called "Practical Binary Analysis" by Dennis Andriesse. Amazing book explains everything perfectly.
8 months ago
Preaty easy in comparasion with R* chalenges