You Do Need power plug adapter while traveling from Samoa to French Guiana.

Here is Why You Need An Adapter

The outlet and plug type used in French Guiana are C, D and E and in Samoa is I. This is how they look like.

Samoa

In Samoa, outlets of type I are in use.

Type I

French Guiana

In French Guiana, outlets of type C, D and E are in use.

Type C

Type D

Type E