Disable form function

Dear all, I need your help.

As a company we want to provide PDF documents to our clients, that they can fill out and then send out to their customers. However, we ran into problems on how to save them, so that the customer cannot adjust the written text. My colleague with a windows computer had no issues by saving the PDF via the printing function. Why is this not possible on a mac? And is there another way for our clients with mac to this? 

Thank you!