suerozcelik
Nice Work !
3D Model of old Train
The *.c4d file includes textured (HDR map) and redshift materials which are without any textured or map so you can use it easily. The *.obj and *.fbx have the only model and don't include textures. If you need a model with textured and HDR map you need to download *.C4D If you need only the model then you can download *.obj or *.fbx. You need to use redshift to render
HDRI map
HDRI map is free and is downloaded from this website Polyhaven and has CCO License.
Polyhaven - you can visit this website and choose another HDRI if you want.
You can use it how you want.
The only thing you can't do is claim to be the original author or re-license them.