Apple Mail won't sign in to Google account

My guess is Apple will say something like your iMac and OSX is too old, and we don't support it anymore.

Your description is correct. Gmail is requesting this info from the Apple Mail app, and my computer is not setup properly, or is missing something somewhere, that Google Gmail requires. I'm already using Apple Mail with two other Gmail accounts, so clearly whatever Google needs, it's only an issue when the account is created in Apple Mail. So to me, this all means Google has moved on to more advanced authentication than my version of Apple Mail supports (because it is so old).

This apparently happened in May 2022, per this thread: Apple Mail won't sign in to Google account - Apple Community

That thread claims they have the solution, which I tried to follow. But I started this thread because that thread is closed. I just wanted to know the where and how I use the 16 character password.

I guess I'll just try to contact the person that claimed they have the solution. I was sure I was just not understanding something as it wasn't being explained, but I guess not.

Thanks, but now I'm more confused. The message refers me to the app developer (Apple), and you're referring me back to Google. This problem has happened before. I've seen many references to it online, and have tried all the "solutions", except the one I am asking about in this post (where to enter the 16 character App PW). So this suggestion isn't very constructive to me.

Maybe you can address what the issue refers to? That the "...app doesn't comply with one or more Google validation rules."? Do you know what this is referring to? Do you know how to provide what Google requires? Someone must know what is needed here.

As I said, there are solutions out there. This post title I used is actually the exact same one of a previous post that "solved" this. It was already closed so I couldn't reply to it, so I created a new one with the same name in the hopes that those who worked on it before would clarify.

Hi, Thanks for responding. I should have been more clear. I already have several Gmail accounts in Mail. I do not want to remove them. Recently, I tried to add a third Gmail account, and I get the following shown below (something I never saw before, and which I do not see on my MacBook Air; I am only seeing this on my circa-2011 iMac High Sierra computer). I read if I sign up for two-factor authentication, and get an App password (which I did), then I can get past this. But what I am asking is where do I enter this 16 character password? I see no place to enter a password anywhere as I cannot get past that pop up. I am positive that if I were to remove either of my working email accounts, and try to add it back, I'd run into the exact same issue. I hope this clarifies the question. Thanks.

I already did that, in both my Google account and my Apple account. In either case, it generates a 16 character password. The original question to this post stands: Where do I use this?! There is no place that I can see in Apple Mail where I can enter the Gmail address and password because I get that pop up, which doesn't allow input. What am I missing here? Am I supposed to do this in a different way then selecting Google to create the mail account in Apple Mail, or what?

Found a solution, and posted it here:

https://discussions.apple.com/thread/254692276

That's exactly what others were told in other threads, and it got them exactly nowhere!