Per Nomagic's wiki, it needs browser-extension how-to completing.

These are steps towards a draft:

Install the Wallabag extension for your browser by following the instructions at https://doc.wallabag.org/en/user/articles/save.html#by-using-a-browser-add-on.
Login in to your Nomagic Wallabag account and click on 'API clients management'
Click on 'Create New Client'.
!["nomagic create new client.png"](nomagic create new client.png)
You need to complete this step and the following for each browser and smartphone client that you want to access your Wallabag account.
!["name client.png"](name client.png)
Nomagic's Wallabagger service will provide 'Client ID' and 'Client secret' credentials for the client:

Configure each client with its own details, obtained this way.

How to sync your smartphone account.
Wallabag's own documentation for installing it on your smartphone is clear and well-illustrated.

Obviously, this is a work in progress. Posting it here in case it helps until I can finish it off.