Seems legit to me:
1. US:
https://www.usa.gov/visitors-driving
2. CAN:
https://travel.gc.ca/travelling/documents/international-driving-permit
3. CAA:
https://www.aaa.com/vacation/idpf.html
4. Wiki:
https://en.wikipedia.org/wiki/International_Driving_Permit
If you take a moment to read those sites, it explains what it is, and isn't. How it may benefit a person to have it.
There is an FAQ on the CAA link at the bottom that answers a lot of common questions.
There are also warnings that are many scammers out there taking advantage of it.
Notable points:
1. You can only get it in your home country, for use abroad.
2. The IDP must be accompanied by a valid driver license issued in the applicant's country of residence.
3. Motor Vehicle Associations are responsible for issuing them (ie: AAA, CAA, etc.) and governments recognize them.
4. According to the table on Wikipedia; Dominican Republic is a part of the 1949 Geneva Convention, which states that an 'International Driving Permit' remains valid for one year from the date of issue, with a grace period of six months.
Canada, USA, and Dominican Republic are for example are a part of the 1949 Convention...