If Condo owner does not pay their monthly dues what recourse does the association have?

You can read your governing documents and confirm that your monthly assessments may represent an automatic lien against your title, upon which the board can act when you don't pay your assessments. You may also have a personal responsibility to pay your assessments.

In addition, when you fall behind in your payments, the association is required to pursue you for the debt, to and including the sale of your unit to satisfy what you owe, plus expenses of collection.

Read your governing documents to fully understand the process involved in collecting assessments.

In sum: The association can place a lien on the property equal to the amount owed. If the lien goes unpaid, the association can foreclose on the property and take legal ownership of it.
The amount of the lien may include attorney's fees and expenses.