Hello friends.
Congratulations to the new owner of Twitter.

With your help, I was able to find tweets in a twitter list and add them to my favorites list with my own software. However, I only do this on my own account.
My aim is to make the same transactions with the accounts of different units of our NGO using this application.
Is this possible and how?

If you own the accounts (can log in the browser) you can do something like this:

Then using the access token belonging to the account will make calls on behalf of the user.

If you do not have full access to the other accounts, you will need to implement this whole flow so that someone else can step through and give your app the access tokens: Log in with Twitter | Docs | Twitter Developer Platform