I had the same problem on Big Sur 11.0.1 Beta where I had both Docker App 2.5.0.0 and Virtualbox 6.1.16 installed. I had to remove/uninstall Virtualbox to get the Docker App to run. I tried several versions of Virtualbox, but to no avail. Both VB 6.1.16 and Docker 2.5.0.0 run well on Big Sur 11.0.1 Beta but only when one is installed without the other. In other words, VB can only run when Docker is uninstalled, and vice versa.
Does anyone has an explanation for this and/or a suggestion to get them to work side by side?