How to change booking admin_url for Confirm

Hi, we use a security plugin which gets rid of the public version of the wp-admin login URL. However the Restaurant Reservation plugin still assumes that wp-admin is the path, so when I try to click the confirmation link from a reservation email, it goes to a broken link. Is there a place I can hardcode or replace the wp-admin with a new URL that I can key in to be stored there?

Thanks!

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