What you get with a free account on ridewithgps might be more than you need.

The 520 has a world basemap (not a lot of detail). You can load small maps to it that have more detail. (There's limited space for maps.) But the 520 only displays the map.

All of the Garmins (500+) provide basic "track following". This includes displaying a the course (track), making a noise and displaying a notification when you go off-course, and simple and small turn notifications (called "course points") which include an icon (usually an arrow) and a short street name. There aren't that many ways of getting the "course points". Ridewithgps writes its cuesheet entries as "course points" to the "tcx" files that it exports. Some of the "track following" units might be able to generate notifications based on an angle in the track.

One problem with "course points" is that they get displayed at the turns (it's more useful to display them before the turns). Ridewithgps has an option to move them earlier in the track (but that feature you have to pay for).

You can use "tcx" files or "gpx" track files on the Garmins (both work the same except the tcx files can have "course points").

The Garmin units that use maps (not merely display them) have an additional "turn guidance" mode that shows big white arrows about 0.1 miles before the turn. This "turn guidance" mode can be enabled for both tcx and gpx files. The "turn guidance" mode is much clearer than the "course point" notifications but the "turn guidance" mode can sometimes stop working.

The units that use maps can also generate routes (like a car navigation unit does).

The units that use maps are the 800, 810, Touring, 820, 1000.