When I try to download & install Flash Player for Win 10/ Firefox it says 'complete' then on last page it says 'Here is another product that might interest you' and the install never completes.
I removed the previous version and also checked Add-ons to make sure settings were correct.
I run Kaspersky and Malwarebytes, but have given permission to run from Adobe.com.
If you're getting to the 'Here is another product that might interest you' page then it indicates Flash Player installation completed successfully. To confirm, launch Firefox and go to https://helpx.adobe.com/flash-player.html. Click the 'Check Now' button. The system information widget should return the OS, browser, and Flash Player version.