Change the script as per following
Set Variable [ $FileName ; Value: "Test_" & Substitute ( Get ( CurrentDate ) ; "/" ; "-" ) & ".pdf" ]
Set Variable [ $PDFPath ; Value: Get (DocumentsPath) & $FileName ]
Save Records as PDF [ No dialog ; "$PDFPath" ; Records being browsed ]
Send Mail [ Send via E-mail Client ; To: "firstname.lastname@example.org" ; Subject: "Invoice" ; Message: "Test" ; "$PDFPath" ]
The PDF is stored in same location where the fmp12 files are on iOS devices. It is the application file folder of FM Go, where we transfer/store the fmp12 files to accessed using FM Go.