Let's use a private browser when logging in to QuickBooks Online. Private browsers don't use any extensions which may cause an interruption when connecting your PayPal account.
Please also make sure that you're using the master admin login when accessing your PayPal account. Then, follow these steps to connect it:
Here are some articles that will help you further:
Use the Connect to PayPal app
Connect to PayPal FAQ
Let us know if you have other questions. We are here to help.