The first time you open BiteSpeed, you'll get a prompt to connect your Facebook page in the onboarding itself. You'll just need to select the page you want to connect to BiteSpeed.
It's quite simple generally but let's talk about some of the problems you might run into.
1. If anything goes wrong on the onboarding page where you are asked to connect your Facebook page, click Refresh.
If there are any issues like the Facebook button not appearing, or wanting to connect a different Facebook page, just click refresh.
2. Do you have admin level access to the Facebook Page you trying to connect?
Only users with an admin access to the Facebook Page will be able to connect the page to BiteSpeed.
You can check this by going to your Facebook Page > Settings > Page Roles.
3. Is your Facebook page not listed on the connect Facebook Pages list ?
From your personal Facebook account, go to Business integrations.
Here, click on BiteSpeed (view and edit) and in the dialogue box that opens make sure that the checkbox against the Facebook page you want to connect is checked.
After this, just save and try to reconnect. You can also try logging out of BiteSpeed and Facebook and logging in again.