Curtain set created in Blender using cloth simulation features, cloth brush, textured, and ready to use in archviz or VFX projects.

To import into your scene go to File>Append, navigate to .blend files folder, open the file, open "Group" folder, then double-click on the name of the group and append.

Or you can just select it and copy it using CTRL+C and in your scene pressing CTRL+V.

Textures are from cc0textures.
HDRI maps are from HDRI Haven.