Hey, so I had this problem as well, and the solution is fairly simple. You just have to open the webconnector seperate from the management console and start flash. This can be done by simply Googling "Teamviewer WebConnector" as it should be the first result. You can then go back to the management console, reload te page, and the option to use it shouldn't be greyed out anymore. I believe this happens because it believes that you won't be able to use it as you don't have flash, but upon activating flash it works just fine. Hope this works for anybody still having this problem!
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