How to save Bitdefender VPN Premium to an iPad Air

I have managed to save the VPN Premium to my uPad Pro but I'am having difficulty saving it to my wife's ancient iPad Air.

1) From the email that I sent to her device, I click on "Download now".

2) I then click "Download Bitdefender VPN".

3) The next screen "bitdefender flowed by a long row of digits". Below this, I click on "Open in 'Files''".

4) I then have two options:

4.1)" iCloud Drive"

4.2) "On My iPad".

I click "On MY iPad" but nothing happens!

Any help would be much appreciated.