To reproduce this issue:
1) New Liferay installation
2) Go to Marketplace | Store
3) Add a application that is > 3MB (ex: ETL process manager)
4) Go to Marketplace | Purchased
5) Click on download
6) Download never ends
To fix this issue:
1) Configure portal-ext.properties and increase "dl.file.max.size" (ex: dl.file.max.size=30072000)
2) Restart Liferay and retry.
3) Works as expected
I'm expecting the Marketplace app to show some warning / error to the end user to avoid confusion about why the download doesn't work.