Is that the full error message or is there more?
Could you post a screenshot of the message so we can see the style of message box? That sometimes clarifies where the message is coming from.
It looks like something to do with the installer rather than Opus itself, so you may find reinstalling and rebooting resolves it. Check the installer's digital signature to make sure it was not only partially downloaded or anything like that:
Antivirus can also block parts of the installer or make it crash. Check your antivirus software's logs in case they indicate anything is happening.
The second-last suggestion in this guide may be worth trying, if still having problems: