Marek, the correct way to install WX5 onto a new computer is to visit your profile (top right, this screen), go to download to get the installable and retrieve your license from my licenses.

Is this what you did?

You should also note that to transfer your project/s the correct way is to go to your old pc, run wx5 and open your project, go to step 5 export project to create an iwzip file, copy the iwzip file to the new pc, open wx5 and import the project.