There is no pro advisor option on the side above my books. How to make it appear?

Where is your company located? QBO Accountant version is only available for limited regions. 

I’m in the Philippines. What are the possible solutions for this? Can this be accessed through a VPN?

If you work as an accountant for a company based in the Philippines, they offer a free trial account for 2 months. But I'm not sure if it's QBO Accountant for the Philippines version. You may need to access your client's QBO account as a Company Admin (unbilled user).

https://quickbooks.grsm.io/Philippines-Accountants

Hello, brylle-vincent-I.

I agree with Fiat, that you may need to access your client's account as Company user. 

I'm adding this articles for additional reference:

• Add and manage users in QuickBooks Online.
• Managing accountant users in QBO.

Keep me posted for any updates regarding your concern. I'll keep an eye on your response. Have a nice day!