I am writing my dissertation and my supervisor recommended me this LaTeX template.
https://bitbucket.org/amiede/classicthesis/wiki/Home
However, I have been using MS-Word all along and don't know LaTeX. What are some approaches I can consider given this situation?
Learn how to use LaTeX.
LaTeX is not hard. If you have any experience programming you'll probably find LaTeX extremely elementary. You can conceivably have issues rendering certain characters or equations, but Google is likely to easily find solutions to that. TeX is also quite powerful as a word processing tool, allowing you to write obscure symbols (for example, \cdot) easily. This doesn't mean LaTeX is better than Word; certainly some things are easier done in Word than TeX. But knowing both means you have an additional weapon in your arsenal, and you'll have a better idea which weapon to deploy given what you intend to write in your dissertation.
First, the repository you linked to has a PDF showing exactly what the template looks like. So, there is really no issue, you can follow that template in whatever typesetting system you want. This technically answers the question you asked -- you can follow your advisor's instructions and still use Word. I hate to see you waste time recreating everything in Word when it already exists in LaTeX, however.
A better option would be to search for thesis templates written in Word. Depending on how flexible your advisor is, you could either tweak the templates until they look like the one your advisor wanted, or you could sit with your advisor to find one you both like, or you could just find one you like and see whether he complains.
An even better option, assuming you are in STEM, would be to learn LaTeX. This is something you should know anyway if you are getting a STEM degree. You'll be able to copy-and-paste your existing text into LaTeX (with some minor modifications); you don't have to type it all out again. Assuming you know how to program, you'll learn LaTeX in about 90 minutes -- read chapters 2 and 3 of "The Not So Short Guide to LaTeX." If you don't know how to program, this will be a heavier lift, but it's still a low-effort, high-reward endeavor.
One last point -- are you sure your institution doesn't have a required thesis format? Most universities I'm familiar with are very particular about how thesis should be formatted, especially the front matter -- mine even had institutional templates floating around, in both Word and LaTeX.
Edit: One last, last point: Elizabeth makes an interesting distinction between a writing program (where you write your content) and a typesetting program (where you make it look nice). If you share this concern, you could always continue to do your drafting in Word, and then set aside a few days at the end to TeX-ify it (or hire someone to do so). I personally would find it more efficient to use TeX end-to-end, but to each their own.
The issue here isn't whether LaTeX is hard to learn. The issue is that a LaTeX editor is a terrible writing environment when compared to a word processor. Some people are bothered by this and some are not, and which side you're on is entirely a matter of personal preference.
What is not a matter of personal preference is the expectations of your supervisor and your field. Some fields (and some supervisors) regard producing LaTeX-typeset documents to be matter of professional necessity. Others just think it looks nice, or they like the tech-cred pretentions. So it's impossible to give a good answer to your question without knowing what your context is.
EDIT: This doesn't add much to answering the OP's question, but judging by the comments there seems to be some confusion about what a word processor is for, as well as about what a downvote is for.
Word processors were specifically designed for writing documents, and have features such as outline view, tracking changes, commenting sidebars, etc. Moreover, many writers use formatting features such as highlighting and font color as part of their writing process.
TeX on the other hand was specifically designed for typesetting documents, and the introduction of LaTeX and its variants made it a marginally usable system for writing documents. But the standard LaTeX front ends don't have the features of a word processor and many people find having to read around markup cumbersome and distracting. For these reasons, using a word processor is an objectively better environment for writing.
Of course, many other people are perfectly happy writing in a text editor and don't mind reading around markup. But this doesn't make you smarter, "more efficient," or a superior human being. It just means that you have a different work process.
The point for the OP is that being expected to trade Word for LaTeX is generally a lousy deal, but there might be constraining or mitigating factors in any particular situation.
