I am updating my project from PHP7.4 to PHP8.0. During this process, the PHPSpreadSheet library gave this error. When I opened the Settings.php file, I saw that the CacheInterface really did not exist. I opened the repository and downloaded it from there, inserted it into my project, but it still gives this error when executing, but the code does not give any error.
Due to company policies, I cannot use composer. How can I install PHPSpreadSheet correctly manually?