Siemens Logo Soft Comfort V7.1.5 Free Download -free- [best]

(if you are writing for a technical audience)

The trial version can open and convert V7.1.5 projects without issue. So you don't really need the old version.

If you have an old licensed copy of V7.1.5 on a CD-ROM or backup, install it on a Windows 7 or Windows 10 virtual machine (VMware or VirtualBox). This keeps legacy software running without affecting your main OS.

This is the core question. Let's break it down.