How?
Technically, Simple Server Currency doesn't need a bank system because it saves player cash when they leave the server. All you have to do is enable Script_Player_Persistence and Support_Player_Persistence. But, if you still want a "bank" (like an ATM or a Bank building) you can use VCE and 2 bricks:
Deposit button would look something like this
Here is a withdrawal button: withdrawals cost 4 dollars per transaction
In the above example, I paired it with promptEvents, and made it save/load items also