Open source software has existed long before the invention of the (D)VCS. The author likely hosted a barebones HTML webpage or a txt file describing the project. There definitely was an FTP server somewhere with tarballs. The author may have been reachable by email. If you were really lucky …
Nothing I ever write will be popular and I won’t ever force myself to work on my own projects I dont enjoy. Everything I write is without warranty nor guarantee.