PayPal Live payments do not work

Hello, 

We are trying to set up PayPal live payments.

We have newly installed v6.

We tried to set different options under "Live Id*":
a) our paypal business email - Live Paypal account
b) Client ID from API credentials
c) Secret key from API credentials

None of options seems to work. We always get same error:
“Things don’t appear to be working at the moment. Please try again later.”

The URL of the error: https://www.paypal.com/webapps/shoppingcart/error?flowlogging_id=f32704210e60f&code=INTERNAL_ERROR&mfid=1687772444732_f32704210e60f

Can someone help us? Thanks in advance!