Answer: Yes, you can still install and activate a plugin with this notice.
Of course, it is better to use a plugin that you know is compatible with the most recent version of WordPress (and you did upgrade, didn’t you?).
The compatibility of a plugin is determined by actual users who vote on whether or not it is compatible on their site. Yet another reason why using an open source software like WordPress has its benefits.
So, if you have the choice, go for the plugin that is already compatible.