hey no problem!
leerspielung means, that there are no more coins left in your gamestation.
wirtegeld means, that he now want you to fill in the money he wants to put out.
so if wirtegeld is shown on the display, you have to put 280€ in coins in. after that, you can do a cashout. if done, the message should be gone and you should be able to play again.
if you dont have so much coin money, you also can put in lets say 50€, do a cashout, and the message leerspielung will be shown again at the moment there is 230€ left on the geldspeicher display. now the wirtegeld message comes again, and you can fill in 50€ again. do this as long as there is money at the geldspeicher left. if the geldspeicher display is at zero, youre done