getting sessions error when attempting to access Admin area, help!!

I just installed the newest Maian Stripe. Not only did it hang during installation (I eventually refreshed the browser and it appears to have installed), but now I get this error when trying to go to the Admin area:
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Session save path (/var/lib/php/sessions) does not exist, is not set, or does not have write permissions. Please fix in PHP.ini file (session.save_path) and reload page.
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That folder *does* exist, and I tried changing permission of it to 777, and it is set as the default sessions folder in my PHP 7.4.29 settings. Can you help? I've finally got Stripe going and have already had a sale so I'm verified now. Thanks!