Reckon the question isn't the map file but firmware which is different. You can find firmware files on an enthusiasts web site mibsolution.one you need to start the address as https and the login names is guest. Password guest. The site is often down / overloaded. There is no help there but a user repository of files, no instructions. There is a mib enthusiasts Facebook page and Telegram chat area where like minded people chat.
People get themselves into trouble loading firmware themselves on mib3, so it appears. Largely outside Europe where connect services isn't supported and dealer networks are poor. I wouldn't advice attempting to change the firmware yourself in these conditions since if you mess it up, you are stuck.
One of the board sponsors who did sell the firmware with instructions stopped selling it and put themselves onto the dealer only type of arrangement since I believe due to the complicated nature of it. @East Yorkshire Retrofits may like to comment.
In Europe there are two main types of units for mib3 denoted by the xxx or yyyy firmware code. One having the extra character on it. Both have navigation. If yours doesn't have navigation then it might be like the mib2 type of ones, specific firmware for non sat units. Cut down. That would then make it a third thread of firmware for a third hardware model that isn't found in the UK to my knowledge.
My overall view if you live outside of a dealer supported area don't mess with the firmware else you might end up in deep trouble. You find that on boards for mib3. In the UK @East Yorkshire Retrofits has sorted out over the years posters messing up mib2 hardware via DIY by having the units mailed to them. If you don't have a local retrofitter with experience to fall back on DIY isn't a good idea.
@cairus might have something to say who does mess with mib3 firmware and may place your model In relation to the mibsolution.one repository of files. All may or may be lost.