On Frog, click on "Add a connection" and select Stripe.
For the title, you are free to name it as you want. If you plan to use several Stripe connections, be sure to differentiate them.
Then open a new tab on your navigator and go to your Stripe account.
Now,you will find your Publishable key and your Secret key here : https://dashboard.stripe.com/apikeys
Copy-paste the publishable key (or revoke it to get a new one if it is too old)
Generate a new secret key if you haven't got one already.
Warning : The secret key will be shown once by Stripe at its creation. After the pop-up is gone, you will not be able to have access to it anymore.
So be sure to write it down somewhere safe.
If you happen to lose this key, your only solution will be to revoke it in order to get a new one.
To revoke a key, just click on the three dots at the end of the line to open a menu and then click on "Revoke key..."