The answer to your question - which is basically (a) can the association restrict your ability to rent your unit and, if so, can they fine you for renting in violation of a rental cap - is found in the governing documents for your association. Your agent may have been wrong in stating there was no rental cap. Or, your association may have adopted a rental cap after you purchased the unit (although you should have received notice of a proposed amendment if that is the case).
You need to sit down and review the declaration, amendments, and any other governing documents for your association to figure out whether your association is applying its governing documents correctly. You may wish to do this with the assistance of an attorney experienced in community association law. There is a link below to help you find a referral.
If your association has a properly adopted rental cap and if it is enforcing the cap in accordance with its rules and regulations/rental policy, you may be stuck between a rock and a hard place.
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