I got problem with admob closed block, plz help me

Hi guys,
when I close the ads I want to start download as you seen in this img

but problem is
when I close ads it works
but again I close ads then its download starts again

I want to, when I close ads if pdf not download then download
if downloaded in file then open

plz help me

CustomDownload by Deep Host ?
Use this instead -

initialize downloaded = false
And do when FileStatusDownload Completed if filename = pdf
then set downloaded to true

When ad closed if downloaded = false then start download