I agree, you are probably missing one step somewhere. The important clue is "Include route calculation data" not being available. I think MapSource is not sending that data as a result.
So, here are the steps that work for me. I will probably write more detail than you need for most of it.
1. Open MapSource and load one of the ACA waypoint files.
2. On the Routes tab in the left pane, click one of the routes, then View > Show Selected Route on Map.
3. On the Maps tab in the left pane, if any maps show in the list, click on each and press your Delete key to delete it.
4. Activate the Map tool: Tools > Map. Click near the middle of the route on the map. The map will change color, indicating that this map segment has been selected. If any part of the route lies outside that colored area, click there to color it too.
5. Now you should see one or more map segments named in the Maps tab. Check the box "Include route calculation data."
6. Connect your 60Cx receiver and turn it on.
7. In MapSource, Transfer > Send to Device. Check Maps, Waypoints, and Routes. Click Send.
8. When the transfer is complete, locate the Routes page in the 60Cx menus. Select the route you just loaded and navigate it, choosing Follow Roads.
OK, if these steps do not work for you, please write back where the procedure fails and in what way. This should get you there soon.
Different routing from MapSource and the GPSR is common, even when their routing options are set the same. They clearly use different routing algorithms. The ACA routes should have enough intermediate waypoints to keep the GPSR on the route you want. In fact, they have many more than are necessary.