From what sampradaya did he take sanyasa ?
Was it from the dashanami sampradaya ?
Yes, Chaitanya Mahaprabhu took initiation from the Dashnami Sampradaya.
When Lord Caitanya Mahāprabhu went to the temple of Lord Śiva known as Kapoteśvara, Nityānanda Prabhu, who was keeping His sannyāsa staff in custody, broke the staff in three parts and threw it into the river Bhārgīnadī. Later this river became known as Daṇḍa-bhāṅgā-nadī. (Chaitanya Charitamrita, 2.5.143)
This is confirmed by Srila Prabhupada, the founding acharya the Gaudiya Vaishnava organization ISKCON (who was strict opponent of Advaita Vedanta) himself in his purport to this verse:
The mystery of the sannyāsa-daṇḍa (staff) of Śrī Caitanya Mahāprabhu has been explained by Śrīla Bhaktisiddhānta Sarasvatī Ṭhākura. Śrī Caitanya Mahāprabhu accepted the order of sannyāsa from a Māyāvādī sannyāsī. The Māyāvādī sannyāsīs generally carry one staff, or daṇḍa. Taking advantage of Śrī Caitanya Mahāprabhu's absence, Śrīla Nityānanda Prabhu broke the staff into three parts and threw it into the river now known as the Daṇḍa-bhāṅgā-nadī. In the sannyāsa order there are four divisions-kuṭīcaka, bahūdaka, haṁsa and paramahaṁsa. Only when the sannyāsī remains on the kuṭīcaka and bahūdaka platforms can he carry a staff. However, when one is elevated to the status of haṁsa or paramahaṁsa, after touring and preaching the bhakti cult, he must give up the sannyāsa staff. Śrī Caitanya Mahāprabhu is Śrī Kṛṣṇa, the Supreme Personality of Godhead. It is therefore said, śrī-kṛṣṇa-caitanya, rādhā-kṛṣṇa nahe anya: "Two personalities-Śrīmatī Rādhārāṇī and Śrī Kṛṣṇa-are combined in the incarnation of Śrī Caitanya Mahāprabhu." Therefore, considering Śrī Caitanya Mahāprabhu to be an extraordinary person, Lord Nityānanda Prabhu did not wait for the paramahaṁsa stage. He reasoned that the Supreme Personality of Godhead is automatically on the paramahaṁsa stage; therefore He does not need to carry the sannyāsa-daṇḍa. This is the reason Śrī Nityānanda Prabhu broke the staff into three pieces and threw it into the water.
Btw this is not the only instance in Prabhupada's commentary on the Chaitanya Charitamrita where he admits Mahaprabhu to have taken initiation from the Dashnami Sampradaya. He has admitted in his commentaries on Chaitanya Charitamrita 1.3.34, 1.7.34 and 1.10.40 as well.
However, at the same time, it can be argued using the incident of Nityananda breaking Mahaprabhu's staff into three parts to symbolise Tridandi Sannyasa.
Another instance in the Chaitanya Charitamrita where Chaitanya Mahaprabhu is shown to be initiating in the Dashnami Sampradaya is present in the Chapter 7 of Adi Lila:
Seeing that the Māyāvādīs and others were fleeing, Lord Caitanya thought, "I wanted everyone to be immersed in this inundation of love of Godhead, but some of them have escaped. Therefore I shall devise a trick to drown them also." Thus the Lord accepted the sannyāsa order of life after full consideration. (Chaitanya Charitamrita 1.7.31-33)