Why the focus on one brand/product (Vanguard/VTI) only?
Availability of and access to Vanguard ETFs/funds will differ from market to market. And depending on the trading situation in your country, you might be faced with high spreads, high trading costs, currency conversion cost or low liquidity.
Instead, if you want to start passive investing now, I would just scan the market for any broad-market ETF available at your local online brokers. Any ETF tracking S&P500, MSCI World, FTSE All World or similar with an acceptable total expense ration (e.g., <0.3%) will work for your start in passive index investing. If you are an expat in the UAE, I would also keep the ability to transfer funds to other countries (e.g., your home country) in mind.
Unfortunately, I don't know about the specific situation in the UAE, but I would just check out what some of the local online brokers offer and then work with that. Local resources and groups might also help you with selecting the right broker and products (see e.g., the local Bogleheads chapter
https://bogleheadsuae.wixsite.com/website).
In their blog, you can access a few member presentations about passive investing in UAE.
Edit:
A few more links that you might find helpful:
Discussion on UAE brokers at Bogleheads (
https://www.bogleheads.org/forum/viewtopic.php?t=149175)
Article on ETF investment in UAE (
https://www.thenational.ae/business/your-essential-guide-to-low-cost-funds-and-etfs-1.193289)