First, navigate to the campaign where you'd like to connect the TikTok Ads integration, then click "Integrations" from the menu on the left side of the screen.
Click on TikTok Ads in the list of available integrations.
Then click "Connect New Account".
You'll be prompted to select the account you would like to connect. Click the radio button next to the appropriate account, then click "Connect".
If the account that you would like to connect is not shown, click "Connect New Account".
A popup will appear asking you to log in to TikTok Ads. Enter your credentials and follow the prompts.