I want to install mybb with one click installer and someone said they would not recommend doing that, does the one click installer have any problems with installing mybb forum
It depends on the one click application, usually there should be no difference between the manual and once click installation.
"I wouldn't recommend doing that" isn't a valid concern, unless it's backed up by arguments and reasons for the concern. Ask for reasons, why this would be a bad idea, and so on. Because, as @RoseHosting said, there usually isn't anything different from installing it yourself, and doing it via the one-click install, the latter is just quicker.
Like all the others said before there shouldn't be much difference or concerns. I have used both (one click install and installed it myself) the only thing that was different for me was the version. The one click installer version was a bit outdated, so I installed it manually. That does not mean it is the same case for you. Check the version to see if it is the latest one before you do. Even if it ain't you can update it after.