Hi @Gerben Wierda:
Unfortunately, Adobe only makes the current version and the last version available for download through the Creative Cloud Desktop app. In the past, people have reported success getting installers for older versions from Adobe support, but I've been hearing with some regularity that it hasn't been happening lately. Given the issues with InDesign 2024, you may have a better chance of asking and receiving the installers directly from the Adobe. If the first person says no you could ask for their supervisor.
Adobe Customer Care
https://helpx.adobe.com/contact.html
1 (800) 833-6687
That said, 18 should be stable unless you are on either on early version of macOS Ventura or you upgraded already to macOS Sonoma. Are you on a Mac? If so, I can give some more detail.
~Barb