a feeling of not being certain about something —macmillan
Doubt is often seen to be used in a sense that there is question whether certain things is going to happen or to be in a certain way, in other words, certain thing is true.
There seems to be some doubt as to whether this is legal.
The above example states there's question whether "this" is legal.
But can we use doubt in the sense of "inquiry"?
I found the works from the site you gave me, but I have doubts about how it works.
The above example is clearly trying to say "I don't know how it works". It's more of a question asking than really expressing a feeling about certain things is true.
Is this usage correct?