What is the group "al-Thaqalayn" that adopts Ahmadiyya, and is the Hadith "Hussein is from me, and I am from him" authentic?

The Hadith: "Hussain is from me, and I am from Hussain. Allah loves whoever loves Hussain. Hussain is a grandson among the grandsons." Graded as Hasan by Al-Tirmidhi and Al-Albani, this Hadith indicates the virtue of Hussain (may Allah be pleased with him). The Sunni Muslims love and venerate Hussain, pledge allegiance to him, and bear witness to his entry into Paradise, but without the extremism of the Rafidah and the Shi'a. They do not invoke him besides Allah, nor do they believe in his infallibility or his knowledge of the unseen. They do not harbor hatred for or declare the Companions as disbelievers, nor do they disparage Abu Bakr, Umar, Aishah, or others. It is feared that the group "Thaqalayn" might be Shi'ite, so beware of that and adhere to the path of the Ahl Al-Sunnah Wal-Jama'ah.