Fillet or blend two surfaces into smooth curve

HelloI am trying to fillet the two edges of the flat surface and the corner of the cylinder to avoid the sharp 90 degree angle. See in picture. I tried using fillet edge, fillet corner, and blend edges but nothig works… Does anyone has any tips on how to proceed?
Thank you

Hi Celeste - please post the file or send to with a link back to this topic in your comments.