I use this website, webassign.net, to do my assignments online. For some functions, the website needs flash player. The problem is that I have downloaded flash player from adobe.com and installed it several times and still the site does not accept it.
All major browser vendors block Flash by default and prompt the user to enable it when Flash is detected. If you're not being prompted, it's most likely due to the Flash detection scripts on the page not being written to comply with the browser detection requirements.
Depending on your browser, you can try whitelisting the exact page that has the Flash content. For example, if Flash content is on flash.webassign.net then you would whitelist flash.webassign.net, not webassign.net. Alternatively, you can whitelist all sites by adding https://* and http://* to the whitelist
See the instructions to enable Flash in the various browsers at https://helpx.adobe.com/flash-player.html If these instructions don't help, please provide the OS and browser (including version for both) that you are using.
I also recommend reporting this to the folks at webassign.net as the onus is on them to ensure their site complies with the constantly