I am designing an event invitation card and would like to add a clickable button that will open Google maps to a specified location for directions. How do achieve this in a PDF file?
You would need to be able to make a link to a URL (thing starting https) and add it to the PDF. This isn't really about PDFs, it's about Google maps. I think Google do offer some advanced tools for making URLs to an exact location; you might have to sign up as a developer.
Create a button in your page layout software (like InDesign), open the pdf in Acrobat and go to Tools> Prepare Forms, right click the button to edit the button properties, copy the web address of the google map and paste it into the button.
I have tried this, and it's working (but only on the PC). When I try to click it on different phones it doesn't work, irrespective of the app I use to open. Can I send the file over and the link for you to assist me with it?
You are not doing anything wrong, some pdf viewers, particularly on phones, do not support pdf buttons, probably for security reasons.