I installed Tor browser from https://www.torproject.org to my Windows machine. The size of the browser is 137 MB instead of 65 MB as shown in the installation instructions from the Tor's website. Did I install the real Tor? Thanks in advance!
There are at least two questions lurking in your post, so let me try and sort them out.
- Could the size of the thing you installed be different from the size described on the torproject.org site?
- How do you know whether the Tor program you have is really the one that was made by the Tor project? (Note that I have plagiarized this question from the Tor project!)
If you want to be sure that you installed a genuine version of TBB then you must follow the advice given by the Tor project developers, and check signatures and so forth. Answering your question about size will not confirm whether you have a genuine copy of TBB. At best, it might tell you that you do not have a genuine copy.
Now to the first question. The installation executable that you downloaded from the torproject should have been of the size they described (give or take differences in the way you calculate megabytes). The installation bundle, however, is a compressed package; when you run the installation executable, it will be decompressed and, on my machine at least, the Tor Browser folder contains about 157 Mb of files; in other words, the decompressed bundle is much larger than the installation executable that one downloads.
Now, having read this, and before you do anything else, you should learn how to verify your installation bundle!