How do I create an account

Well, you don't! All polls are managed through your password, which is used for things such as poll deletion.
Entering a password is not mandatory, but if you don't enter one, then you won't be able to modify your poll!

How do I embed a poll?

That's simple! Add something like the below code somewhere on your website. For the embed style, there's currently DefaultLight and DefaultDark.

<iframe src="https://pollbay.net/polls.php?id=[your poll id]&embed=1&estyle=[the embed style you want]" style="width: 100%; max-width: [max width. e.g. 500px]; height: [the height. e.g. 500px]; max-height: [the max height. e.g. 800px]; border: none;"></iframe>

What do the options mean?

There are two options currently available for general Pollbay users. The first one is called "Disable IP check." When you vote, your ip address is logged which makes it so that you cannot vote again, but turning this off will disable that check and allow the same ip to vote over and over again.
The second one is called "Hide votes." This one makes it so that nobody can see votes until you decide to unhide them.

Why isn't Pollbay open-source?

Because the code is messy and I don't want to deal with that part too much at the moment.