you can go to the “register snap” page of your user account on snapcraft.io … it will tell you the package name is already taken and offer you a “dispute” button or link, where you can ask to take over the name then …
note though that this would have to be a classic snap and
does not actually have a category for file managers, neither in the supported nor in the unsupported list, i personally doubt you will get classic granted for this (though i’m not a reviewer)
