I recently tried to install Lazarus 1.6.4 (3.0.2) 64bit onto a Windows 10 64bit computer.
It installed well, but it would not run or compile any apps. An error message was that it could not find the IDE config file. Another was, Illegal parameter: -Twin32.
I wasn't able to determine what that had applied to.
I also saw nothing where I could manually direct it to the IDE config file (I had created a separate folder for its files, because I had also installed as an independent compiler). So I uninstalled, and reinstalled. It still gave the same errors.
I then tried to install Lazarus 1.6.4 (3.0.2) 32bit. It behaved well with all my apps, and they would run and compile. No errors.
The drawback is that they are 32bit, and for most of them, I have to set their compatibility modes. Mostly because they do ActiveX to interact with other programs.
Additionally, I was able to use Anchordocking with both installs, but I did have to re-enable the Coolbar, as others have said. It was a bit of trouble to figure out how to do so. The setting wasn't anywhere that I would expect.
Rick