I probably got a little ahead of myself saying "download page". In any case, you're right, but it might still install, although I'm pretty sure it's not going to run the way it's supposed to on low-end devices, if it runs, of course.
I recently had to use an old phone and I could not even install telegram there, let alone other apps. so no, it can not even be installed.
If a phone is, say, 4 years old it can be called old, but not necessarily old enough to not install some apps. I could install telegram on my iPad 4, it's 5 years old by the way, but I couldn't get it to run. So, there it is.