The True-VDB addon can be found in the N panel in the 3D viewport, under the True-VFX tab. Follow these steps to use the addon:
Open the True-VFX tab in the N panel.
The first alphabetical asset for the default category will be displayed. Click the icon to open that category and view all the assets inside.
Once you have chosen an asset, click the "ADD VDB VOLUME" button.
The volume asset will be added to your scene in a new collection called "Volume." When you add more assets, the collection will be suffixed with a number to keep them separate.
The BASE empty object can be selected to move the asset around in your scene.
You can play through your timeline and switch to Cycles render view to check out the asset.
If you want to change the starting frame of the animation, select the volume object, go to the volume panel, and modify the "Start" value. Negative values will push the start of the animation back by the chosen number of frames, while positive values will start the animation early by that number of frames.