HELP! Stepmania on Mac.

i download it successfully but my keyboard is not responding to ANYTHING. i hit enter or the arrow keys literally nothing happens. im stuck on the starter page :c

There's a weird bug nobody has been able to figure out that sometimes causes a blank key config on OS X.
Find ~/Library/Preferences/StepMania 5/Keymaps.ini and post its contents. Try deleting it after posting its contents, it should be regenerated with a valid config when starting Stepmania.
The Docs link has more info on finding the folder. (I'm on Linux, so I'm not 100% sure of the path, so it might be inside the Save folder at the path listed in the Docs)


Side note: Next release will have an option in the debug menu for rescuing people from a bad key config problem.

it now says: [dance]
1_Back=
1_Coin=
1_Down=
1_EffectDown=
1_EffectUp=
1_Left=
1_MenuDown=
1_MenuLeft=
1_MenuRight=
1_MenuUp=
1_Operator=
1_Right=
1_Select=
1_Start=
1_Up=
1_UpLeft=
1_UpRight=
2_Back=
2_Coin=
2_Down=
2_EffectDown=
2_EffectUp=
2_Left=
2_MenuDown=
2_MenuLeft=
2_MenuRight=
2_MenuUp=
2_Operator=
2_Right=
2_Select=
2_Start=
2_Up=
2_UpLeft=
2_UpRight=

Yep, that's what I expected.
If you use my config (pasted below), you should be able to use stepmania and configure the keys as you want.
My config maps the operator key to Dlelete because I don't have scroll lock on this keyboard.
Fill it up with this:

[dance]
1_Back=Joy1_B10
1_Coin=
1_Down=Joy2_B2:Key_s
1_EffectDown=
1_EffectUp=
1_Left=Joy2_B3
1_MenuDown=Key_v
1_MenuLeft=
1_MenuRight=
1_MenuUp=Key_m:Key_pgdn
1_Operator=Key_delete
1_Right=Joy2_B4
1_Select=
1_Start=
1_Up=Joy2_B1:Key_l
1_UpLeft=Key_z
1_UpRight=
2_Back=:Key_q
2_Coin=
2_Down=Joy1_B2:Key_r
2_EffectDown=
2_EffectUp=
2_Left=Joy1_B3:Key_e
2_MenuDown=:Key_f
2_MenuLeft=:Key_d
2_MenuRight=:Key_k
2_MenuUp=:Key_j
2_Operator=
2_Right=Joy1_B4:Key_i
2_Select=Joy1_B5:Key_b
2_Start=Joy1_B6:Key_space
2_Up=Joy1_B1:Key_u
2_UpLeft=
2_UpRight=

ive pasted that into it and it still doesnt work :c

I hate bugs like this because I'm not on a system where I could reproduce them and the things I think of trying don't work.
I can't think of anything else to try, and I'm surprised that pasting in my config didn't at least allow you to do stuff as player 2. (player 2 keys in that config are 'e' for left, 'r' for down, 'u' for up, and 'i' for right, and space for start.)

is there no hope for me ;_;

Quit StepMania.
Paste the contents that Kyzentun shared into your Keymaps.ini, clearing all of its pre-existing contents.
Save the file.
Start StepMania.

Any changes made to any StepMania settings files while StepMania is running are ignored and eventually overwritten. Thus, the fist step is critical; quit StepMania first.

Can you use your keyboard now?