If you just started, you’re definitely not used to it, if the fatigue its so bad, you should lower the intensity a notch and/or the volume and/or the frequency to give your body a break to adapt to this new form of working out. You can also replenish your glycogen storages post workout with some fast digesting carbs (depending in your goals) and make sure you hydrate. If the issue persists for more than a week, you should look at your diet, are you eating enough carbs? Do you eat enough vegetables? Do you have a multi-vitamin-mineral supplement? Fix that if needed to ensure no nutritional deficiencies are happening. If the issue persists, you should look at your sleep patterns. Fix that if needed. If the issue persists, run some bloodwork, something’s probably wrong with you. It’s always better to go to the root cause of issues rather than to put band-aids on it. Supplements that can help with fatigue are creatine, beta-alanine and rhodiola.
Let me know if this helped.