(TechNote) The Flash Player may fail to install due to incorrect permissions in the registry. Before you download the Microsoft tool and follow these instructions, try this first: How to fix almost all Flash Player issues.
Additionally, if you don’t have administrator access, then you may not be able to install the Flash Player successfully. Permissions can be tricky but, in general, you should be able to install and use the Adobe Flash Player if your system administrator gives you full access. Windows users should be familiar with Registry permissions required for Flash Player install or update (TechNote tn_19148).