Hello kmchong,
Entering the download ID is described in the documentation.
There you will also find all other explanations on all other topics.
Entering the download ID is described on the above-mentioned page.
Update via the Update Manager:
docs.joomla-5.visforms.vi-solutions.de/e...with-update-manager/
Right at the top it describes where you can get your download ID.
Where can I find my download-ID?
docs.joomla-5.visforms.vi-solutions.de/e...-find-my-download-id
Immediately after that it describes what you have to do with the download ID.
What do I have to do with the download-ID?
docs.joomla-5.visforms.vi-solutions.de/e...with-the-download-id
Attention:
It is not enough to buy the product and have the license.
You must install the product to be able to use it on your site.
You must enter your download ID as described above to use the Joomla Update Manager.
Good luck and best wishes, Ingmar
P.S.:
Thank you very much for the informative screenshot from your first post.