First open the floor plan/elevation where you want to add auto dimensioning.

In the toolbar section, go to the "Annotate" tab and click on the type of dimensioning you want to add out of Align/ Angle/ XY/ Radial.

When you select any option, the design panel on the left of your screen will show the settings of how the dimensioning needs to be done. Make the changes your want.

Towards the bottom of the design panel, you can see an option "Add auto dimensioning". Select the same, and dimensions will be added to your drawing.

You can manually add/ change any dimension you need post that.