GitHub code and detailed assembly:
https://github.com/Marcel3245/Tank-and-Controller

I used:

• Arduino Uno
• dc hobby motor 1:48(3~12V
• Battery 7.4V
• Bluetooth module HC-06
• Paper Clips(To connect treads)

To correctly mount the motor, place it in one of the designated holes in the 'Side' part with the projected shaft on the other side, then attach the 'Main cog' part to it. Once done, you can mount the remaining cogs and the side bumper. If everything was printed correctly and cleaned, they should press fit.

After connecting all the tracks (32 for both sides), you can place them on the cogs. Don't hesitate to use a bit more force; it shouldn't break. Additionally, I recommend securing the 'Side' with the 'Side bumper' using rope or paper clips in the middle hole designed for this purpose.

The final step is to guide the cables from the motors between the holes in the body and press-fit everything together. If the clips don't hold it securely enough, you can either try reprinting it or simply use some tape on the bottom – nobody will notice.
Now that you've completed these steps, you're halfway through.