You Do Need power plug adapter while traveling from Spain to Antigua and Barbuda.

Here is Why You Need An Adapter

The outlet and plug type used in Antigua and Barbuda are A and B and in Spain are C and F. This is how they look like.

Spain

In Spain, outlets of type C and F are in use.

Type C

Type F

Antigua and Barbuda

In Antigua and Barbuda, outlets of type A and B are in use.

Type A

Type B