v2.1.0 PayPal Express Checkout configuration

V2.1.0
Working on a new install.

I see in the module's configuration page the fields for:
API Signature -- Username
API Signature -- Password
API Signature -- Signature Code

In an old v1.57
I did have all the 3 info and it worked fine, with the "username" being like myname_api1@example.com the myname and example.com being those of my Paypal account.

Now I can't find any reference on Paypal's site (developer section) data as "username" in the email format, only information is:
App name
Client ID
Secret Key

Also in the module's configuration it's mentioned the "password" as a 16-character code and the "Signature Code" 56-character code whereas the Paypal "Client ID" and "Secret Key" are both 80-character codes

What am I missing, are the tips on Zen Cart not updated, or what?

P.S.
I have a new Paypal account to use, hence I canno use the v1.57 info.

I'm sure it is somewhere at their Paypal site.
I had to look some weeks ago some time, too.
Their site is not that user friendly as it could be.

If you weren't able to find it you should ask the Paypal support where it is.

Thanks.
Totally agree that Paypal site is user unfriendly.
I asked their assistance, but haven't got an answer yet, I mean an answer where to look for it, since the person who answered seemed to not even know what I was talking about.

Indeed I was hoping someone here would know where I could look for it.

consider using PayPal Restful. Much better product.

https://www.zen-cart.com/downloads.php?do=file&id=2382

Thank you.
Didn't know it, will start testing (implementing) it in the next days.