> Open DevTools
> Go to Console tab
> Write this (it's JavaScript)
document.getElementsByTagName("button")[0].innerText
If it returns "Save", that's your button, if it does not, try with 1, then 2, etc., until it returns "Save".
What you're doing here is telling your browser: "Hey, I need you to give me an array of all the button tags in the document", when you add the brackets, you're specifying which element you want from the array, the innerText property is the caption. So, you're basically looking for the button with caption "Save". Assuming that's the only button with caption "Save" in that document, you'll be able to click it.
From VBA, the syntax is very similar, instead of using brackets, you use parentheses, and, instead of using the .innerText property, you'll use .click
document.getElementsByTagName("button")(1234).click
, where 1234 is the number you found.