You Do Need power plug adapter while traveling from Chile to Guinea-Bissau.

Here is Why You Need An Adapter

The outlet and plug type used in Guinea-Bissau is C and in Chile are C and L. This is how they look like.

Chile

In Chile, outlets of type C and L are in use.

Type C

Type L

Guinea-Bissau

In Guinea-Bissau, outlets of type C are in use.

Type C