You might know it: You search an extension with the Typo3 extension and get the message “No matching extensions found”. So you check the name again and try it another time. No change.
One possible workaround is to download the extension as t3x-file manually from the Repository and upload it to your extension manager. But hey, why is there an extension manager? The solution of the issue could be quite simple: You searched an unreviewed extension. Even some popular extensions like w4x_backup have not been marked as verified, yet. To be able to import these unreviewed ones you just go to the settings page of the extension manager and activate the “Enable extensions without review” field. Now you can give the search another try.
Please note: You work around a security check. So do it only if you know what you are doing!