Let's go over setting up the Facebook pixel for your account (which must have a previously connected Business Manager). 
A pixel set up this way passes events to FB such as "registration" and "conversion". If you need to pass other events (for example, "page view") - use the guide Creating and setting up the Facebook Pixel.

Go to the page https://business.facebook.com, click "Connect data sources".

Select "Web".

Enter a name (at your discretion).

Select "Meta Pixel and Conversions API".

Click "Finish".

Click "Set up Conversions API".

Select "Set up manually".

Select two event types: "Purchase" and "CompleteRegistration".

For each, select the following set of customer information parameters (see the screenshot below):

Complete the setup.

After completing the setup, you will be prompted to generate a token.

You can also find it in the pixel settings menu.

Go to the Facebook Conversion API page in the affiliate network, add the previously created pixel (you need to enter the pixel ID and its token, specify an arbitrary name).
Optionally, you can set up a proxy.

The added pixel can be edited if desired by clicking the corresponding icon.

Once the pixel is added, connect it to the target flow via the flow setup form. Select the added pixel and choose which event it should pass. Then save the flow.

For proper operation, the process must be organized so that the fbclid value (Facebook click ID) is passed to the fbclid parameter of the affiliate network's flow link.
Ad campaign optimization is done based on "Purchase" events.