Can't let it work. Confusing translation

Hello,
I just bought this Paypal module but I can't let it work.
Usually I place the API username, the API password and the signature in other carts/modules.
Here the translation ask strange things (I attached).
I try few combination but it does not work, the error is: Client Authentication failed
Please instruct me on how to use it. I am using version 2.2.2
Thank you, bye.
Vilaiporn

I was too fast as usual.
I did create the REST API (I did not even think they exisit) and looks OK for now...

Instructions in the README file :)

yes...

ok sembra funzionare non per mettere le credenziali api ma qualcos'altro

English please