When you are using Matomo Marketplace or updating Matomo a connection is made to matomo.org endpoints. From Matomo 5+ all connections to matomo.org use a secure HTTPS connection by default.
We highly recommend configuring your environment to allow HTTPS connections in order to maintain access to the latest security patches and other important updates for Matomo. This requires that CURL or allow_url_fopen is supported and that the OpenSSL PHP-extension is installed.
If your Matomo instance is unable to support an HTTPS connection you can force insecure HTTP connections to matomo.org by altering the config.ini.php as below
[General] force_matomo_http_request = 1