No.

You can use the standalone .jpg textures in Eevee and Cycles.

If you want to use them as projected textures, know they will only work with Cycles.  So you must have Cycles enabled in order to project lights and shadows. And you have to be in Viewport Shading - Rendered for them to show.

To get that cool volumetric light ray effect, I applied a cube with a Principled Volume node to the scene and adjusted its density. You can find the settings I used in the first GIF.

I also used the same setup on other pics in the gallery. I only adjusted the cube size, location and density.

You sure can! You can animate them by adjusting the color, size, clarity/blur, intensity of the textures and by modifying the node setup provided.

Yes. 

The textures have the .jpg format and work with all Blender versions. The Asset Browser part only works with Blender 3.0 and up.

Yes. 

The textures have the .jpg format and work with all Blender versions. 

Open Blender. Click Edit - Preferences... - File Paths - Asset Libraries - "+", find the file location, click the "1000 Gobos" file, click "Add Asset Library" and you are done! Enjoy!

Yes! You can also modify the node setup included.

The texture projector is made by using the Blender spot lamp together with one of the 1000 textures.

No.