How could I pay the commission via PayPal?

Dear colleagues!

Could you please suggest a way to pay the commission via PayPal? My friend does it using the Pulse app, as a big blue "Pay" button appears at Finance/Invoices section on his phone. In contrast, when I open the same section on my phone, there's no such a button but only the invoice itself. 

What should I do to make this button appear on my phone?

Many thanks in advance,

Best,

Eugene