Manually downloading (installing) apps

What did you do to see them in the nextcloud application (access from browser)?

I am new at this, at nextcloud and generally no data hacker but my friends rely upon me.
however, I have been able to download the zip-files, ftp’d them to the right place and extracted them, being able to see them … but not in nextcloud.

it is the group access and access control apps I want enabled for my business.