As our Garmin Landing Page explains, there are two types of Trailforks Garmin basemaps.
1. Trailforks partnered with Garmin to integrate Trailforks data into a custom MTB map & features on select Garmin Edge devices. The Garmin Edge 530, Edge 830 and Edge 1030 Plus offer the integrated Trailforks features. This basemap includes Trailforks MTB trails, some POIs like Parking lots and TTFs along with riding area markers at lower zoom levels. This map is also routable using the Edge's built-in routing capabilities.
There is no set schedule of when this basemap is updated. Trailforks sends Garmin a data dump 2-3 times a year then Garmin releases the map updated through Garmin Express.
2. Trailforks also produces our own custom Garmin basemap, which can be downloaded on a per-state or country basis. This map includes Trailforks trails, POIs and OpenStreetMap roads. It is NOT routable. This basemap should work on any Garmin product that supports custom basemaps. We also offer a trails only basemap, so just the trails are included and can be viewed overtop another basemap.
We have only been updating these maps a few times a year, however we hope to soon create a more automated pipeline to have these maps update on a monthly basis.