#Firefox seems to have a new profile manager but if you already have profiles created in the old profile manager they don't appear in it and there doesn't seem to be a way to export from old to new.
It looks like there is some sort of transition period, will just have to be patient https://support.mozilla.org/en-US/kb/profile-management
Manage Firefox profiles | Firefox Help

Learn about the new Firefox profile manager and how to create, customize, manage and switch profiles that you use for different purposes.