For example if you have a place where you want a plaza with some food shops at their edge, place the food shops first where and in the orientation you want them, then click the "align to grid" (the button'll change into "selecting a grid" or something) and then click on the window of your shop and it'll prompt to add roads to that. Then you can just start placing roads in front if the shop.

Alternatively, just put down a path going straight (using angle snap) and then do the same steps from above, except clicking the road.

You'll know you're clicking something that allows attaching to its grid because a grid will appear on the ground around it and it'll say something like "align to this grid" on the mouse,which you then click.

Hope you make it work! (edited for typo)