check extension is installed on browser.

Hey Kaii, 

The extension is used only in chrome so its only chrome you need to check 

https://support.smartbear.com/testcomplete/docs/app-testing/web/general/preparing-browsers/chrome-extension.html

Have you multiple instances of chrome? 

For other browser prepparation the steps are different so see the below link for reference

https://support.smartbear.com/testcomplete/docs/app-testing/web/general/preparing-browsers/index.html

Hope this helps 

Vinnie