Check out this list if there's an exchange that's compatible and supporting fiat withdrawal in your country.
--> https://www.bitrawr.com/the-dominican-republic
--> https://www.bitrawr.com/the-dominican-republic
I've seen that website but I don't really trust it since it contains Kraken which actually doesn't do fiat withdrawals to the Dominican Republic.
Check out this list if there's an exchange that's compatible and supporting fiat withdrawal in your country.
--> https://www.bitrawr.com/the-dominican-republic
Or simply through local bitcoins .. https://localbitcoins.com/country/DO--> https://www.bitrawr.com/the-dominican-republic
I heard also that coinbase supported Dominican Republic https://www.coinbase.com/places/dominican-republic , I'm not familiar with coinmama though. Better choose coinbase if i were you.
You can also explore currency exchange board here https://bitcointalk.org/index.php?board=53.0 , if you feel comfortable you might get in touch with people near you but yeah i knew it, privacy is number 1

Goodluck.
Coinbase doesn't support fiat withdrawals to the Dominican Republic either according to their website: https://www.coinbase.com/places/dominican-republic
I know about localbitcoins but it's usually a bit more expensive than exchanges in terms of fees. Would really like to know if one of the major exchanges supports wire transfer to DR bank.