Renting doesn't mean bare walls. For most prints up to A2 on 240 gsm paper, Command Poster Strips are the most reliable option - they hold well, come off cleanly, and don't sag over time.
For very light unframed prints, washi tape at all four corners is our favourite low-effort trick. It peels off paint without lifting anything and looks intentional.
For a rotating gallery, a magnetic poster rail (wooden strip with magnets, hung from a single small nail) lets you swap prints in seconds and only leaves one tiny hole.
Skip putty for larger prints - it drys out, discolours the paper, and leaves oily marks on the wall.