wikipedia says https://en.wikipedia.org/wiki/Versions_of_Ramayana
"Ananda Ramayana is traditionally attributed to Valmiki. While it briefly recounts the traditional story of Rama, it is composed primarily of stories peripheral, though related, to Valmiki’s narrative. This ramayana provide information about last years of Rama's life. These include Ravana’s abduction of Sita and Rama’s installment of the Shiva Lingam at Rameswaram."
"Ananda Ramayana is a Sanskrit text traditionally ascribed to the sage Valmiki, who is also credited with the Adbhuta Ramayana, Valmiki Ramayana, and the Yoga Vasishta (Vasishta Ramayana). The text has received little attention from scholars to date, though in some traditions it is considered one of the principles sources of Rama stories."