Best Tools for Building Slide Decks Without a Designer

Hey all, I know this seems slightly outside the ops but I feel like it's ops who always have the answers. My question is: Those who don't use designers to build slide decks, what tools do you use that allow you to build slide deck templates quickly without a ton of design knowledge needed? Full story for anyone interested: We've got no in-house designer, we're trying to build a few branded revenue team decks for pitches, products, investors ect. We hire an outsourced design team who I tasked with building a deck, provided content and slide layouts we liked the idea of for each. They came back with plain slides with headers and the logo, technically branded, but not really hitting the brief. After feedback, including detailed information about why I'd chosen specific slides, what I liked about them eg: 'I chose this slide for this information because I want it to feel like easy broken down steps a prospect can take to solve their problem' they came back with something slightly more designed or, there was more blue on the page based on our brand colours, but the actual layouts were the same as what they'd presented before. Follow up questions based on the story for anyone who read it, I've never managed an outsourced design team, should I be giving them briefs on what I want things to look like, or is that the issue, should I just be saying 'be creative' and letting them get on with it?