New Magento 2.2.5 installation needs the patch that changes the MD5 key to a SHA_512 key using a new signature_key. The patch updates the [login to view URL] payment gateway.
Please do not bid unless you know about, understand, and have successfully applied the patch required.
Work to be done on a vpn (anydesk, teamviewer, ?) to a local workstation with an SSH terminal having full root access to the Magento server.