How can I save an entire webpage as PDF in Safari?

You can do this via Safari Print > PDF > Save as PDF, though Safari isn't as good at this as Firefox's Print > Save as PDF.

Ain addition to...

Safari File > Print... > PDF > Save as PDF

...with some options for background, and headers and footers ...there is also...

Safari File > Export as PDF...

which has somewhat different output. I usually try both and see which one I like better or sometimes try to do that with another browser.

Open the multipage web site in Safari. File menu > Print… > PDF > Open in Preview or Save as PDF. This produces a multipage PDF for me on macOS Sequoia v15.5.

Making assumptions in the following, given the lack of background info on the requirements and plans…

Open Text Edit app somewhere, and then on the webpage, select-all, copy, switch to Text Edit, and paste.

This assuming you’re planning on using the names and addresses, and have no better path to export.

Yeah, you can need to reformat the text. Same reformatting applies with the PDF.

If you want to get a little more fancy with Shortcuts and web scraping:

https://www.reddit.com/r/shortcuts/comments/ae80co/quick_and_dirty_guide_to_scraping_data_from/

Processing the HTML text itself can be another option, and that may be faster depending on the page rendering.

If what you are looking at is a true HTML table spanning three pages, then you may be able to copy and paste that into a first single-selected cell of a Pages word processing document table and it will autofill that table. This would not be true if it were a pure CSS formed table using flex display style and no HTML table elements.