I've tried this too. But, the Import failed.
Basically, Export Squarespace to WordPress XML. Import to another Squarespace from the WordPress XML = failed.
So, in my case, I can't even get the partial transfer completed.
Is my only option to actually go to WordPress?
Seems that way.
Seems like a missed opportunity for Squarespace. I'm actually being directed AWAY from the other Squarespace sites I pay for.