Program Download - IE CHROME - "is not commonly downloaded and could be dangerous."
The best resources are this blog post and this blog post.
To sum up:
- Sign you package with an authenticode signature.
- Don't be malware (I'm sure you got that covered).
- Logo your software (if it's not a browser plug-in).
This can be a frustrating process, so hang in there. Microsoft has not disclosed how many downloads one needs to build a reputation, but in practice once you stop changing the package (the hash is part of the reputation) then you can get past this fairly quickly.
I've fixed this by uploading the file to Google Drive (you can convert the Google Drive share link to a direct download link using some online converter).
Now my executable downloads without warning. Silly but it works.