trying to transfer from old computer

You don't.  Adobe applications need to be installed using installation files.  Find your serial number so that you can activate the installation after you install it.

Download and Installation Help -

https://helpx.adobe.com/download-install.html

Lightroom - all versions

Windows

http://www.adobe.com/support/downloads/product.jsp?product=113&platform=Windows

Mac

http://www.adobe.com/support/downloads/product.jsp?product=113&platform=Macintosh

Lightroom 6

https://helpx.adobe.com/lightroom/kb/lightroom-downloads.html

https://helpx.adobe.com/creative-cloud/help/download-install-single-app-Lightroom-6.html

Find your serial number