During the extension installation (via Component Manager in Magento backend) I got some weird message in Readiness Check step (PHP Settings section).

“Your current PHP memory limit is 2048M. Magento 2 requires it to be set to 768M or more. As a user with root privileges, edit your php.ini file to increase memory_limit. (The command php –ini tells you where it is located.) After that, restart your web server and try again.”

So, if my memory limit in php.ini is set to 2048MB, how is that less than 768MB? (and yes, I double checked php.ini on correct location).

Here looks like that issue is not related with memory limit at all, anyway until I find out what is actual problem here this is the workaround if you want to continue with extension installation process.

      Locate file PATH-TO-YOUR-MAGENTO-SITE\setup\src\Magento\Setup\Model\PhpReadinessCheck.php
      Update error variable to false in the checkMemoryLimit function (line 201)
if (
            $currentMemoryInteger > 0
            && $this->dataSize->convertSizeToBytes($currentMemoryLimit)
            < $this->dataSize->convertSizeToBytes($minimumRequiredMemoryLimit)
        ) {
	    //$error = true;
            $error = false;
            $message = sprintf(
                'Your current PHP memory limit is %s.
                 Magento 2 requires it to be set to %s or more.
                 As a user with root privileges, edit your php.ini file to increase memory_limit. 
                 (The command php --ini tells you where it is located.) 
                 After that, restart your web server and try again.',
                $currentMemoryLimit,
                $minimumRequiredMemoryLimit
            );
        }

As you can see, logic for displaying error was correct, but for some reason error gets displayed, and process cannot be continued.

This is just (not so clean) workaround, so if some of readers of this post find real solution, please send the feedback.