The demo version allows you to test the full functionality of the software, including exclusive Pro-tier tools, with certain export restrictions.
Blackmagic Design's DaVinci Resolve is the king of free color grading. While it doesn't have the "Hue Twist" grid exactly like 3D LUT Creator, it has and Color Warper (introduced in version 17). The Color Warper is a grid-based tool that allows radial hue shifts. It is not identical, but it is incredibly powerful and 100% free (no malware).
If you need to create and export your own LUTs without any cost, these industry-standard tools are your best bet: 3D LUT Creator - official site
Lattice is a free (donationware) tool for Mac and Windows. While it doesn't generate LUTs from scratch easily, it allows you to edit existing 3D LUTs.
Most camera manufacturers (Sony, Canon, Blackmagic) provide free "technical" LUTs to bring your footage back to a standard Rec.709 look.
: A free utility available on the Microsoft Store for building custom color grading pipelines. 3D LUT Creator - official site