There would probably be many schools of thought regarding the need to manually fertilize a garden plant... ;-) But I don't think a little 5-10-5 would hurt at this juncture. The beauty of that native vine is its flowers and evergreen habit so sometimes you need to balance the potential of rampant vegetative vine growth and few flowers if over-fertilized, with the desire to get some decent vine growth to support a mass of blooms.

You'll want to observe what it does this season and might be surprised that it doesn't need anything at all! But again, observation through a season or two will be a good guide outside of getting some soil tests done to see if any nutrients are lacking.