The existing Advance Reminder Days value controls the one advance reminder. Example: value 2 means an email 2 days before the payout/invoice due date.
Agreement renewal reminders continue only on their configured milestone days (for example 60, 30, 15 and 7 days).
Upload the ZIP to /home2/doctorlabs/public_html/jan.doctorlabs.in, extract, and overwrite existing files. No database upgrade is required.
Your cPanel cron should run /home2/doctorlabs/public_html/jan.doctorlabs.in/cron/erp_reminders.php once daily, preferably in the morning.