You mean this mod?
https://www.nexusmods.com/witcher3/mods/7408 Are you want only this mod? Then in game folder just create new folder name: Mods
Copy unpacked mod folder modfreecam_beta and paste in to this Moda folder.
then open in notepad file: input.settings ("C:\Users\[your username]\Documents\The Witcher 3\input.settings)
And put this bellowed text at the end of input.settings note and save file:
[Boat]
IK_F2=(Action=FreeCamToggle)
IK_Pad_LeftThumb=(Action=FreeCamToggle,State=Duration,IdleTime=0.8)
IK_LShift=(Action=Sprint)
IK_Pad_A_CROSS=(Action=Sprint)
IK_Space=(Action=Jump)
IK_Pad_B_CIRCLE=(Action=Jump)
[BoatPassenger]
IK_F2=(Action=FreeCamToggle)
IK_Pad_LeftThumb=(Action=FreeCamToggle,State=Duration,IdleTime=0.8)
IK_LShift=(Action=Sprint)
IK_Pad_A_CROSS=(Action=Sprint)
IK_Space=(Action=Jump)
IK_Pad_B_CIRCLE=(Action=Jump)
[Combat]
IK_F2=(Action=FreeCamToggle)
IK_Pad_LeftThumb=(Action=FreeCamToggle,State=Duration,IdleTime=0.8)
IK_Space=(Action=Jump)
IK_Pad_B_CIRCLE=(Action=Jump)
[Combat_Replacer_Ciri]
IK_F2=(Action=FreeCamToggle)
IK_Pad_LeftThumb=(Action=FreeCamToggle,State=Duration,IdleTime=0.8)
IK_Space=(Action=Jump)
IK_Pad_B_CIRCLE=(Action=Jump)
[Diving]
IK_F2=(Action=FreeCamToggle)
IK_Pad_LeftThumb=(Action=FreeCamToggle,State=Duration,IdleTime=0.8)
IK_Space=(Action=Jump)
IK_Pad_B_CIRCLE=(Action=Jump)
[EMPTY_CONTEXT]
IK_F2=(Action=FreeCamToggle)
IK_Pad_LeftThumb=(Action=FreeCamToggle,State=Duration,IdleTime=0.8)
[Exploration]
IK_F2=(Action=FreeCamToggle)
IK_Pad_LeftThumb=(Action=FreeCamToggle,State=Duration,IdleTime=0.8)
[Exploration_Replacer_Ciri]
IK_F2=(Action=FreeCamToggle)
IK_Pad_LeftThumb=(Action=FreeCamToggle,State=Duration,IdleTime=0.8)
[Horse]
IK_F2=(Action=FreeCamToggle)
IK_Pad_LeftThumb=(Action=FreeCamToggle,State=Duration,IdleTime=0.8)
IK_LShift=(Action=Sprint)
IK_Pad_A_CROSS=(Action=Sprint)
IK_Space=(Action=Jump)
IK_Pad_B_CIRCLE=(Action=Jump)
[Horse_Replacer_Ciri]
IK_F2=(Action=FreeCamToggle)
IK_Pad_LeftThumb=(Action=FreeCamToggle,State=Duration,IdleTime=0.8)
IK_LShift=(Action=Sprint)
IK_Pad_A_CROSS=(Action=Sprint)
IK_Space=(Action=Jump)
IK_Pad_B_CIRCLE=(Action=Jump)
[JumpClimb]
IK_F2=(Action=FreeCamToggle)
IK_Pad_LeftThumb=(Action=FreeCamToggle,State=Duration,IdleTime=0.8)
[SCENE_IS_STARTING_HACK]
IK_F2=(Action=FreeCamToggle)
IK_Pad_LeftThumb=(Action=FreeCamToggle,State=Duration,IdleTime=0.8)
IK_Space=(Action=Jump)
IK_Pad_B_CIRCLE=(Action=Jump)
[Scene]
IK_F2=(Action=FreeCamToggle)
IK_Pad_LeftThumb=(Action=FreeCamToggle,State=Duration,IdleTime=0.8)
IK_A=(Action=GI_AxisLeftX,State=Axis,Value=-1)
IK_D=(Action=GI_AxisLeftX,State=Axis,Value=1)
IK_W=(Action=GI_AxisLeftY,State=Axis,Value=1)
IK_Pad_LeftAxisX=(Action=GI_AxisLeftX)
IK_Pad_LeftAxisY=(Action=GI_AxisLeftY)
IK_S=(Action=GI_AxisLeftY,State=Axis,Value=-1)
IK_LShift=(Action=Sprint)
IK_Pad_A_CROSS=(Action=Sprint)
IK_Space=(Action=Jump)
IK_Pad_B_CIRCLE=(Action=Jump)
IK_Escape=(Action=IngameMenu)
IK_PS4_OPTIONS=(Action=IngameMenu)
IK_Pad_Back_Select=(Action=IngameMenu)
IK_U=(Action=EnablePhotoMode)
IK_Pad_LeftThumb=(Action=EnablePhotoMode_Step1)
IK_Pad_RightThumb=(Action=EnablePhotoMode_Step2)
[Swimming]
IK_F2=(Action=FreeCamToggle)
IK_Pad_LeftThumb=(Action=FreeCamToggle,State=Duration,IdleTime=0.8)
IK_Space=(Action=Jump)
IK_Pad_B_CIRCLE=(Action=Jump)