Here is a fixed version of the file. I've set it up with a 50' grid with 5 snaps.

Here's the exact steps to set up a reasonable grid:

1. Right click the Snap button in the lower left.
2. Hit the New button in the dialog to define a new grid
3. Select 2d Rectangular as the grid type and hit continue
4. You can name the new setting whatever you want, but it is best that it follows the actual settings, so I named mine "50, 5 snap". I then set the snap divisions to 5, and the X and Y spacing both to 50. What this ends up doing is making a snap grid that has a visible dot every 50 map units (feet), but it snaps every 10 feet. If you feel the the snaps are too fine grained, try setting the snap divisions to 2 instead, and if you have too few snap points, try with 10 for snap divisions.
5. Click ok, and then back in the select grid system dialog, scroll down and click on your newly created grid to select it, and then hit ok. This will make your new grid the active one. Save the map.

Not too fond of how the text glow visually looks more of a blob behind the text rather than an outline of the text. I suggest reducing the blur radius, or switching to the Outer Glow effect instead.

Actually, you have used the wrong symbols to just put them closer together, you need to use the "middle" symbol, you have three "starts" on the left side, and three "ends" on the right side.

Since the ribbons have the same shape, they should be replaceable without too much work though.

These maps are great as player handouts. I love how they describe the route and let the players know what to look for and what to expect without giving them a complete detailed regional map.

I currently have my players following a river with such a map in hand.

Try to first reboot your computer, then follow up by installing the latest update for CC3+ (downloadable from your reg page) before trying to install CD3 again.

There are also cases when antivirus software have interfered with the installs, so it is also worth trying to temporary disable your antivirus software. You can also ensure that the install really does run with administrative privilegies by right clicking the installer and select run as admin instead of just double clicking on it.

If none of that helps, I recommend you contact tech support.