If you have shell-access to the server running Matomo you can use these built-in commands:
./console searchengines:import-google --idsite=[idSite]
./console searchengines:import-bing --idsite=[idSite]
Normally the imports should be run automatically as Matomo tasks. If you experience some issues or the imports don’t run, you may try to trigger the imports manually to check if they are working at all.