Install the add-on with commands:
apt install splynx-paypal-rb
Settings are complete.
And now , the customer can add his payment card to the portal page:
for this To do so he should login to his PayPal account and click to on [ Agree & Confirm ].
That is all. Client Configuration Completed's configuration is completed.
At last, you can charge all customers using one button! Go to Finance → Invoices, set period and click "Charge" as on the screenshot: