Moved this to Artemis sub-forum for better handling. It's probably because Win Downloads, the site you are using, adds unwanted and possibly risky additions to the download.
Try Open Office themselves perhaps?
Strange. SiteAdvisor rates this site Green, Microsoft Smartscreen Filter says nothing about it.
The site is packed with links to download all sorts of software from big-name players. Why, apart from the convenience of having all those links in one place? What's in it for them?
I clicked to download the Open Office installation program and McAfee blocked it with a Red download warning. So I checked the site URL and download URL with VirusTotal : nothing found.
I downloaded the file (758K, so it's only an installer) and uploaded the file to VirusTotal for checking. Nothing untoward found (0/58). Even McAfee passed it as okay.
The trouble with installers is that they can foist other programs on you as part of the installation process and perhaps that's what this is all about.
I would certainly recommend going to the official source to download Open Office (as I have already done). Watch out if it tries to get you to install Java, you only really need it for one part of the suite (Calc, perhaps).
This file has been analysed and confirmed to be valid detection, as it includes Adware. As mentioned by Ex_Brit and Hayton, it may be preferable to download the OpenOffice suite from the official website provided by Ex_Brit.
Thanks & Regards,