First time question here, so Please forgive/guide me if I'm not doing it right, Thanks !

I'm testing elementary OS 5.1.7 Hera (fresh install from elementaryos-5.1-stable.20200706.iso, I did NOT tweak the OS/install using stuff in terminal or anything). I already had some app updates, including "OS Updates" using AppCenter. All those worked fine and didn't bother me with password stuff and all went smoothly afterwards.

I also installed some other apps using AppCenter : Firefox, Fondo, Norka for example and all went nicely and requesting NO password ...

Now I'm trying to install a .deb (the DownloadVideoHelper.net "companion app") and I found out that to install it I could :

• install it from AppCenter : in Files (app), right-click on the .deb file and select "open in AppCenter" : that option wasn't present, so I added it (by selecting what app to use for that extension), and when I then used it, it didn't do anything ... (well, AppCenter starts and then stays there on the "Home" tab [it is not frozen/hung, it just doesn't do anything more than that]) ;
• install using "sudo apt install ./somefile.deb" : apt requires password, so I'm stuck again.

I searched how to install packages in this os and I found that Synaptic Package Manager would be a great alternative choice, so I tried to install that.

Again in AppCenter, searched for synaptic, found it and when I try to install it (by clicking the "Free" button), it wants a password. To check anything else, I tried installing "FreetuxTV" (just because that one fell under my gaze). Same thing : stuck for a password. But this is non-curated, so I thought this could be the issue here. So I tried installing Badger, also Free, but curated. Same problem : I'm stuck again for a password !

BTW, I tried hitting [Return] at the password prompt, just in case it would accept that as some default, since I read that elementary OS has in-built the "no-password required" concept to install stuff in order to avoid "authentication-fatigue" as they say ...

I believe asking "What is the password / How do I reset the password ?" are thus the wrong questions to ask, since the os developers went for the no-password concept cited above.

So you probably already guessed my question : How do I install any further apps from the catalog (or not), if I'm going to be blocked by this password issue ?

I found and read :

• [https://elementaryos.stackexchange.com/questions/7542/how-can-i-install-deb-files-in-loki] : Eddy might be recommended GUI way, but is NOT Free, so I went for apt "the proper cli way"
• (read all this one but this is the point of interest) [https://elementaryos.stackexchange.com/a/6973]
• [https://elementaryos.stackexchange.com/questions/22504/appcenter-failed-to-obtain-authentication], and sudo apt update / upgrade both block me with a password request. And yes I did reboot ...
• not relevant to my situation but read it anyways (BTW, shouldn't this be in elementaryos.stackexchange ? ) [https://stackoverflow.com/questions/61640553/elementary-os-hera-5-1-cant-login-session-returned-error-code-1-accid]

None of the 25 "Similar questions" (if I counted correctly) proposed when I posted this question were relevany to my question.

Thanks in advance for your help !