Installation: not authorized ?

Computer was hacked and was taken to the computer shop to be cleaned. It was cleaned so good that the boot disk disappeared and only the MacOS remained. Now the Mac keeps looking but can't find anything. So I try to install the 17 Parallels I'm told that this can't be done because I don't have the authority to do so.That pertains reason that present Parallels must be closed. Also the error had popped-up something like there is no partition. I really wish that windowsOS would be the main OS because my usage is used many times over the MacOS. The reason that U like Parallels allows the usage of a better screen than any other that I've seen.

 

Hello,
could you provide us with the screenshot of the error message, please?