The built-in crouch/uncrouch probably doesn’t work because you have not checked “CanCrouch”. You can find this setting under Character Movement Component | Nav Movement | Movement Capabilities | Can Crouch.
For jumping, you can override the CanJump() function of ACharacter. In your Blueprint to the lower left there is a section called Functions. If you hover your mouse over the + sign it will show you “Override”. Click that and select CanJump from the list.
You can’t disable the collision for your capsule component. It’s the basis for the whole movement system, that’s why you can’t move anymore. Rather than having a separate crouch collision, you should decrease the half height of the capsule component to crouch.
