Hey no worries!
Before you wipe the server, be sure to make sure you have the most up to date RustEdit.dll installed, just in case that's why your oil rig card readers aren't working. There will be other electical things not working in the map as well if this is not installed. RustEdit.dll is required for all custom maps to run correctly. https://github.com/k1lly0u/Oxide.Ext.RustEdit
That 4 digit code is for the alarm on oil rig. This is a vanilla feature, if the players use that code on an RF Frequency alarm in their bases, they can get a notification for when it the alarm is going off. There are also alarms for other monuments like excavator that have 4 digit codes the players can use as well.