Blitz3D isn't 'made for Windows 11' (not sure anything is yet?) but I haven't had any reports of it not working on Windows 11 yet either. What are the issues you are experiencing?
But Blitz3D is getting pretty old by now, and it's pretty likely it wont be a 'comfortable' choice for users who are used to more modern tools. It seems to be mostly popular with people writing retro games these days.