Why am I being charged to file a one state return by e-mail?

You got the software to prepare a state return, however there is an extra fee to e-file the state.   You can avoid paying the fee if you print sign and mail the state return instead.

But I bought the Deluxe version with 5 free federal and one free state

.

You do get the one state software to prepare your return, and can file by mail for free. There is a fee to file via e-file. @LifeofRiley3