Currency and number fields on the miniExtensions form support the same formatting options as Airtable:
Comma, period (1,000,000.00)
Period, comma (1.000.000,00)
Space, comma (1 000 000,00)
Space, period (1 000 000.00)
To set the correct format for your region, navigate to:
Your form's settings
Fields list
Click on your currency or number field
Advanced section
Adjust the Thousands and decimal separators setting