You Do Need power plug adapter while traveling from Cyprus 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 Cyprus is G. This is how they look like.

Cyprus

In Cyprus, outlets of type G are in use.

Type G

French Guiana

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

Type C

Type D

Type E