Dominica is a quiet island with not much traffic outside of the capital and other towns. Even in the capital you’ll find the traffic generally languorous and parking easy to find.
Few pay for parking and in many places you wouldn’t find it if you looked. There are a few parking lots on waste ground but they’ll be nearly empty as most park where they find a space.
There’s little enforcement of parking as much of it is free. The authorities only get involved if there’s a vehicle causing an obstruction.
Disabled drivers won’t find any concessions for them but parking in a convenient place isn’t hard to do and if you need help, the locals will always step in with a smile.