Can I increase the licenses on a Business trial?

Hi, I'm on a business trial plan at the moment and I want to add more license to the team (10 license).

I tried doing it via the admin console in manage license, but it always says payment error, even though I have added the billing method. I tried with different browsers as well and nothing worked (mozila, chrome, opera, edge). I tried managing license from different panels, billing panel and member panel and both did not work and return the same payment error. 

Then I tried to invite 10 people into my team so I can have 10 license, but this also does not work.

The first 2 invitations were sent successfully, but when I tried to invite more people, I get this error. 

How can I increase the number of license that I have on business trial? Or can this not be done at all?

Thanks.