NAS 520 - Any app installation freezes at 45%

my bad - didn't know the installation would change the content of web_prefix

This 520 is running V5.21 and I was going to cat http://zyxel.diskstation.eu/Users/Mijzelf/zypkg-repo/ into web_prefix but I'm mystified as to where to place the file. Am I mixing up two methods ?
I did browse Index of /Users/Mijzelf/zypkg-repo/NAS520/zypkg/5.20 (zyxel.diskstation.eu) but can't see any way to use the 2 files therein.
Oh - hang on if I go to the file browser I see admin which from the cli ssh is
/i-data/ce916335/admin with 2 subs download & firmware. Create a new subdirectory here and put the web_prefix into it ? Then how does that pull your package from your server and instal it - Is that the
 On the webinterface desktop, open the 'App Centre'. Goto 'Browse->All Apps'. Now there is a cycle icon on the page. Push it. install MetaRepository. Push the cycle icon again.