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!