Has a website ever asked you to download software to use it?
How sure are you that the additional software is actually required?
It is said that a picture is worth 1000 words. I don’t know how many words two or more pictures are worth, but I think they speak for themselves.
If a website requires some “helper software” or it reports an error and offers you to install something (a code, a viewer, etc.) to solve the issue, then don’t install it.
If you really think you need it, go to the source/author of the software required and install it from there. If the website requests you to install Flash Player, go to Adobe.com and get it from there. If an ActiveX object requires installation, then try to view it with a different browser.
Never install something offered on a website that has nothing to do with the respective software.
Most of the time, these packages offered for download they seem to help you satisfy your curiosity faster, but they actually are malicious software. Malicious software are trojans, viruses or ransomware which in the end will do some kind of damage to your system and/or your online identity.
Some good advice is to install an antivirus software which checks in real-time if these programs downloaded are malicious or not.