Hi Nikodemsky,
I hope you’re doing well :).
The translation files should automatically be downloaded, unless you require FTP credentials when (for instance) updating WordPress.
If you’re using a development version, for instance from GitHub, then translations might not always be downloaded.
If the translation files aren’t automatically downloaded, please go to /wp-admin/update-core.php
and see if there are any actions to be taken regarding the translations. A translation update button should be available when they’re present.
If all that fails, please go to the Polish plugin translations page, scroll down and export the .po and .mo files.
Rename those files to match the following:
autodescription-pl_PL.mo
autodescription-pl_PL.po
You can upload those files in the following folder:
/wp-content/languages/plugins
If that folder doesn’t exist (folder permission issues?), you should create it.
From there, it should work as intended :).
I hope this helps! Let me know if you require any further assistance.