i downloaded jp map on openstreetmap website and copied it to garmin folder not renamed it.
i set the map opened,but it can’t display the map like the pic.i thank the extra map can be displayed，renaming is not necessary.
what should i do to fix it
This 2019 update from dcrainer may help
https://www.google.com.au/amp/s/www.dcrainmaker.com/2019/08/how-to-install-free-maps-on-your-garmin-edge.html/amp
You cannot download maps for Garmin from openstreetmap.org
there are plenty of other sites that offer Garmin maps. https://wiki.openstreetmap.org/wiki/OSM_Map_On_Garmin/Download
it is known that there are regular hickups on garmin.openstreetmap.nl, if that happens to be the case, please try one from the list above. I use https://extract.bbbike.org/ myself