I just received my 66i here in the UK.
Other than hiking, its main purpose is as backup navigation device on our boat.
We have full Garmin navigation kit on board, and hence also have the latest Bluechart G3 Vision chart linked to our Garmin account.
In Garmin Express, this map DOES appear under the purchases tab for my Fenix 5 watch (though I can't install it as it is larger than the internal storage of the watch).
Under the 66i section, the map does not appear under purchases, simply saying "There is no content for this device".
The Garmin site would appear to indicate the map/device should be compatible....indeed if you go to maps on the 66i page, it suggest the G3, G3 Vision charts as being recommended purchases for marine charts.
Can anyone point me in the direction of what might be wrong here?