Your download can be blocked by your browser. As far as ZRound is a non-profit project and there are not enough funds, the cost of a software certificate which grant the installer authenticity can't be assumed.
Anyhow, ZRound is built in a secure personal computer having all security updates everyday and with antivirus software enabled and up to date as well.
If you download the software installer from https://www.zround.com you can trust it. If there were any issue with the site security, your browser will warn you. Please be sure there you have a secure connection.
Please follow these steps: