Glad you found a way to get the maps.

What I was trying to say is the SD you were using was a way to make Garmin Express thinks you attached your Nuvi 1490 to it.
It then no longer sees it as a SD card but your nuvi 1490.

That is why I said now add a second SD card or memory stick with the 2 folders "Garmin and Map" so it would see the SD it was asking for.

But seeing you found a work around by installing the map to your PC and then using MapInstall to put it on your nuvi 1490.