This article contains instructions on how to create a Custom Audience from your UID list.
To create a Custom Audience from your list:
Note: You can download a data file template FB created that's set up to help system map your data more easily.
Preview how FB classified your data, then update accordingly. You may need to change your list to maximize the number of identifiers FB can use.
Note: If you're seeing multiple errors, it may be because FB looking for the wrong delimiter (the punctuation mark that separates data points). You can change this by hovering over "modify the delimiter" and choosing a new one.
What you can do with your data:
Keep in mind that all data needs a type to use it, but only some kinds require formatting details. You only see the Choose format dropdown if it's necessary.
Once you're satisfied, select Create & Upload.
After adding your content, FB hash your data, upload it and create your audience for you. This may take a little while if your file is large.
When FB done creating your Custom Audience, FB automatically generate a list of next steps you can take to get the most out of it. You can take one of those next steps immediately or click Done to finish.