@Felipe Resende FranciscaNeural is currently not available for your endpoint or region i.e brazilsouth. You can get the list of voices supported for your endpoint using the list API. This voice can be used in other regions like westeurope where the voice is available in the list. Please try to use a resource from west europe and check if this works for you.
{
"Name": "Microsoft Server Speech Text to Speech Voice (pt-BR, FranciscaNeural)",
"DisplayName": "Francisca",
"LocalName": "Francisca",
"ShortName": "pt-BR-FranciscaNeural",
"Gender": "Female",
"Locale": "pt-BR",
"StyleList": [
"calm"
],
"SampleRateHertz": "24000",
"VoiceType": "Neural",
"Status": "GA"
},