Does my travel insurance cover medical costs upfront or do I have to pay and claim later?

For policies purchased after 10 August 2016, 3:00am UTC, your World Nomads policy is provided through Zurich Insurance Group

O segurado residente no Brasil poderá contatar a equipe de atendimento da Zurich ou telefonar para +55 (11) 2101-2948 a partir do exterior (aceita ligação a cobrar) ou para 0800-014-3029 a partir do Brasil, 24 horas por dia e 7 dias por semana. Email: sinistro.viagem@br.zurich.com

For policies purchased before 10 August 2016, 3:00am UTC
your World Nomads policy is provided through Bupa Global

Who pays depends on what’s happened!

If it’s an emergency situation where hospital admission and/or medical evacuation is required, the insurer covers these costs upfront (provided the incident is covered as per the policy wording, of course).
You or someone with you would need to contact your relevant emergency assistance team immediately so they are aware and can help you.

If it's not an emergency and the costs are not excessive eg you see the doctor at the local medical centre, then you would pay upfront and make a claim online once all treatment is complete.