Yaga requires Pretty URLs... is that a standard Vanilla plugin?
Take a look in the Tutorial category > FAQ thread.
Is this what you are referencing?
also found this: https://open.vanillaforums.com/discussion/29322/pretty-urls
Yes. The embedded linked FAQ have answers and links for a load of info.
The second link (1st pure link) is the one you should look at for the question in OP.
Additionally be adviced: