@Julie,
In your case, you can not install the apps but the library will not installed. You must make another action via your terminal to finish to install the library.
After you can activate the apps.
The terminal command is :
composer require mylibrary
composer update mylibrary
composer update (for all library)
composer remove mylibrary
If you have this message you can not make an update via the administration, you will see just the version installed.
@SuperThin, As i Said ClicShopping, it's better for you to make a manual update.
You can look the apps accross the admin, but it's better to download and install after
Also you can look via Github or via the marketplace.
Some hoster make restriction and its not possible to know before to make a test.