The files that end with .7z are compressed, most modern windows installs can extract the files by just right clicking the file and selecting the "extract all" option. If you do not have this option you will need to download 7zip, which can be downloaded at www.7-zip.org.
What does the error message say? Windows 11 should be able to extract the archive even without installing 7zip. The topmost 7zip download should be the one you want ( Windows x64 (64-bit) ).
Without 7zip:
1. Right click and select "Extract All".
2. Select a destination or just leave as default.
3. The extraction process will create a new folder with all the game files.
4. Open the folder and run HardStuck.exe.
With 7zip:
1. Right click and select 7zip/Extract to "HardStuck.......".
2. The extraction process will create a new folder with all the game files.
3. Open the folder and run HardStuck.exe.
You could also try downloading the game again, if the download got interrupted it might have corrupted the archive file.
The difference between the two files are the API they use, if the vulkan one doesn't work then download the other.(download files for windows x64) Then find the file (ended with .7z), use winRAR or 7zip (youcan find it in the link offerred by the author above), right-click the .7z file and find the "extract",click it. Then in what you've just extracted, double click the .exe file to run the game.