Hai..Hey Joanne!
No this email is not an Invitation to Apply. The first PDF is the document checklist saying what all documents have to be sent via mail(courier) and the second PDF is the application form (AINP Form 012). You have to fill that form and along with other forms mentioned in the checklist print them out and follow the procedure given in the checklist and mail it to them in the address given. Once they assess everything and if they are satisfied you will get a nomination and 600 points added into your EE profile. Once those points are added into your account then in the next draw you will receive an ITA.
I hope this helps!
Cheers
Thanks for sharing the info. I have submitted all documents to AINP (hardcpoy) via DHL on May 2nd 2019. Do you know in how many days they will respond with the acceptance on the matter or in how many days after receipt of the document will they add 600 points to our express entry profile.