Little-known anti-malware programs display warnings, which are often identified as false positive. Nevertheless, it is recommended to recheck the file with your antivirus software after downloading.
We do not have a download file for the latest version (5.4), but you can try downloading it from the developer's site
Download version 2.2 from Mac Informer
Version: 2.2
Date update: Apr 28, 2016
File name: instabro.dmg
Size: 8.9 MB