Someone that gives you more information than needed to answer your question.
Question: Why is my creative blurry?
Correct response: You need a photo/image/logo with a higher resolution.
Over Explainer: All web advertisements are low resolution in comparison to print to keep the file sizes manageable. If you want to resend the image at high resolution, we can try to resize it larger, but bear in mind, typical web ads are 72 dpi as opposed to 200+ for print. Blurriness is usually caused due to low resolution, and web ads are created at a lower resolution than print ads in order to keep the file size down.