Hi @Barbara,
This is possibly an issue with the files_dir configured in your config.inc.php configuration file – either it’s incorrect, or the file permissions on its contents aren’t permitting OJS to store files there. There is more information regarding permissions in this thread: Permissions of directories and config file - security issue
And as part of our documentation:
https://docs.pkp.sfu.ca/admin-guide/en/securing-your-system
I’m not sure if you are the systems administrator for your OJS instance or not, but it is typically the person who is the systems administrator responsible for installation, upgrading, etc. and who would have knowledge of server configuration, who would carry out these changes.
Best regards,
Roger
PKP Team