Filling out a pdf form on macbook

In that case:

“Otherwise, use Apple’s Preview app and insert text boxes in the fields.”

Do you know for sure that the form is meant to be filled out on a computer, and not printed on paper and filled out with a pen?

If it involves confidential information, a lot of companies and government departments still do not accept anything that can be emailed, only by voice phone, fax, or snail-mail.

(Golly ... what's a "fax", Grandpaw?)

If the form has pre-designed, fillable fields, simply position your cursor over the fields and fill them in.

Otherwise, use Apple’s Preview app and insert text boxes in the fields.