Thx for bringing this up.
I reported the issue: https://mantis.ilias.de/view.php?id=29725
Further, the following PR should improve the situation somewhat, see: https://github.com/ILIAS-eLearning/ILIAS/pull/3082
IMO some infos are still missing though. If you find issues in the install.md and found solutions working for you, it would be very kind to provide a PR to the corresponding branch in the ILIAS repo to the install.md, similar to what I did above. Help is needed in keeping this doc up-to-date.