Marketing stuff for our website

Hey, I want to do few advertising catalogues, product pages etc to promote my company, my services and want to share include few designs from CM. Marketing materials on CM like banners you can link to the shop or affiliates won’t work with my industry I need to do few mockups. Question is how can I and if can I use low res files to do so. I have few designs bought already but each advertising campaign is slight different and wanted to have access to marketing materials, samples I can legally use… is there a place I can find it? Most of similar services have such materials.