CSM only works on a completely clean install of GP4. If you have modded GP4 in any way, including installing GP4 Tweaker, CSM might not work.
Tweaker is built into CSM, so you don't need to install it anyway. Look at the
Data\Tweaker\ folder inside the CSM mod.
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Intel NUC 8i3, 8GB RAM, MS Sidewinder Wheel