The error code is caused by having started the installer when the simulator was still running, or too quickly after the simulator has quit. A windows restart will surely fix it.
And no, the installer is not installing in the "wrong" location. It installs in the location YOU chose. And, it's not letting you change the destination, because you already installed another FSDT product before in that location so, while the installer surely allows you to freely choose ANY place to install into, all FSDT products must stay together, that's why, after the first one you install, the others will all defaults there, in order not letting you do the mistake of spreading several FSDT products in different places, which won't work.