Word Doc to EPUB eBook

I have a completed Microsoft Word manuscript that I need converted into a clean, standards-compliant EPUB file. The book is text-only—there are no images to place or resize—so default styling that mirrors the headings, paragraphs, and simple lists already present in the document is all I’m after.

What matters most to me is that the final EPUB opens flawlessly on the usual readers (Apple Books, Adobe Digital Editions, etc.), includes a functional, auto-generated table of contents, and passes EPUB validation without errors. Please return the finished EPUB plus any source files you used so I can update future editions easily.