Resin can be painted with the spray paint designed for plastic.
Ken has the answer. Just because you wash it down well first. Then go over it with glass cleaner or alcohol before spraying.
Here's a post that might help - https://homeguides.sfgate.com/paint-resin-furniture-krylon-fusion-paint-75547.html
Take a good photo or section of the piece to the paint department of your home improvement store and ask for their advice on paints and application tools/methods for this project. They have the latest tools and materials and know-how to do a professional job and may have ideas and techniques you may have never thought of.