Yeah there’s no confusion in French because “étage” literally means “floor above ground”, so calling the ground floor an “étage” makes no sense. It’s called “rez-de-chaussée” (“at street level”) or RDC for short. Same as “sous-sol” (“under-ground”).

French	UK English	US English
Nème étage	Nth floor	N+1th floor
…	…	…
3e étage	3rd floor	4th floor
2e étage	2nd floor	3rd floor
1er étage	1st floor	2nd floor
RDC	Ground floor	1st floor	— Street level —
1er sous-sol	-1 floor	-1 floor
2e sous-sol	-2 floor	-2 floor
…	…	…
Nème sous-sol	-N floor	-N floor