How did it go? Did you solve it? This happens when updating/upgrading and the installer is unable to remove or override the exiting files. I just have a similar issue with my install using Brew. From what I can see there are two options.

1. Remove the files from the path - optional - > make a backup of those files first so it can be replaced in case things go wild:

sudo rm -rf /Library/spyder-6

the installation will proceed as expected.

2. Create an environment and install there, for example using conda and install the new version there. This, if one wants to keep the previous version installed in the system.

Other options will be a regular install using pip. Or check if the installed version matches the update/upgrade.

Myself I just went for option 1 and worked without issues.