During installation the requirements check verifies the ability to write to a directory. One of those directories being checked, if the check fails, comes up with this message in a yellow/amber box:

To be able to install phpBB the images/avatars/upload/ directory needs to be writable.

After all of the other checks pass this one remains after the initial installer screen as a persistent box above the administrator information entry fields. One of two things needs to happen here:

1. The text should be changed to something a little more appropriate like maybe: "It is recommended that the images/avatars/upload/ directory be writable for a better forum user experience." (I'm not attached to the phrasing so it can be whatever makes it clear that it's not really required)
2. Leave the text as is but make the check red and be required to be solved before proceeding.