Are you certain that you must have a Firefox account?

I've poked around a bit, and I've gotten the impression that you only need one to sync across devices.

I'm running v 67.0.4 and haven't been required to open an account.

You may need to do some deeper digging to find out what's actually going on.

The new Great Equalizer is the SEND button.

In Memory of Harv: Those who can make you believe absurdities can make you commit atrocities. ~Voltaire