@shadrek-m You can find everything in your customer account at Magix.com
But there might not be a download available if your version of the program is very old. In that case you need your old program discs. Alternatively you can upgrade to the new version.
Assuming you do mean 15 released in 2008 then it is highly likely that the program will have no download or activation slot avaialble in your account at magix.com.
Additionally if you do get hold of the installer it may not install on Windows 10 or 11 due to significant changes in these versions of Windows compared to the Windows versions the program was designed for.