How to guide users to the correct download?

I'm new to StackExchange and found this page because I have an unsolved problem:

We have several products. For this we offer two setups for download. One is for some sort of file synchronization (like DropBox) and the other one is for secure email communication. Sadly, there are always users who simply click the first button they find. It turns out that they do not read a single sentence on that page. And for some of them it is obviously the wrong setup. But then they create huge support effort because they give unclear error description until it turns out they're using the wrong tool...

How would you guide them? I considered some "Download assistant", but I doubt that they would read this. Any other ideas?

This is how it currently looks like:

The "Other downloads" link offers other OS (Windows is auto-detected).

Any idea about how I can better guide them? Sadly, it is about 50-50. So half of the users needs the one, the other half the other setup. It does not help to prioritize one.

Any other ideas?