Just downloaded the program and started working through the tutorial. Draw a simple rectangle and try to dimension it and I get either a new 3 sided line attachment with no dimensions or nothing at all.
Tool > Dimension > Horizontal
Turn on "Free Snap" and "Snap on Endpoints"
Left Click on the Left Corner, Right Click on the Right Corner move the mouse to a third point and left click.
Right Clic to Exit dimensioning.
1. I either get nothing, or
2. I get 2 new vertical lines and a new horizontal lin but no dimensions
As a new user, I can confirm you must go into the Options --> Drawing Preferences --> Dimensions and fix up all the defaults. Generally set them all to 1 for a start. On Windows 7 and Windows 10 systems they are all super small decimals after you first install the program.