If you need Flash, you need Flash - there is no substitute for sites that require it.

If Adobe's test site says you don't have it installed and working, then there is almost certainly a problem of some sort.

Google Chrome has Flash support built in. If it is not working there, the links below might be helpful:

https://support.google.com/chrome/answer/6258784

https://forums.adobe.com/thread/2213951