How can this be sorted "Your administrator has not granted you access to QuickBooks Online Plus. Please contact your system administrator with any questions"?

Hello there, vinyugi.

We can performing the basic troubleshooting steps to determine if the issue is caused of having a lot of stored data in our browser.
 

1. Refresh your browser by clicking the Reload icon or press F5 on your keyboard.
2. Log in to your QBO account using a private browser:

• Google Chrome: Ctrl + Shift + N
• Microsoft Edge: Ctrl + Shift + P
• Firefox: Ctrl + Shift + P
• Safari: Command + Shift + N

If the error doesn't appear, let's clear the cache from your main browser. It helps to prevent any unusual behavior when using QuickBooks Online. Also, you can try these compatible browsers in QuickBooks to experience QBO efficiently. Here are they:

• Google Chrome
• Mozilla Firefox
• Microsoft Edge
• Safari 11 or newer (Mac only)

Also, you can check these articles for additional references about QuickBooks:

• Manage Your Account.
• Manage Customers and income.
• Manage Suppliers and Expenses. 

Let me know if you have other questions. Take care always and stay safe.