But how can they be Shias if they follow the Sunni way? Sorry I'm not Muslim
Okay so there are many types of Shias. Shias in Arabic means *group*. So the word you see today as Shias is Shian e Ali. (group of Ali ibn Abi Talib). It started when there became two groups after Prophet's death. The group who refused to accept caliphate was called Shian e Ali. The term was later used for referring to Pro Alid people or armies or groups throughout the history.
So now these Zaydi Shias aren't the regular twelver Shias (98 percent of the Shias are twelvers). Shias believe in 12 Imams (Leaders) from the family tree of Prophet's daughter Fatima.
However, Zaydis are called Fiver Shias. Because when the 4th Imam's son received the title of next Imam. There was a group of followers loyal to his brother named Zayd. Zayd was militarily active and ran covert activities against Ummayad rulers to avenge the massacre of Imam Hussain and his followers in Karbala. While the designated Imam whom majority of Shias followed. His name was Baqar. Baqar did not believe in Military approach of his brother as he was well aware of the deceiving nature of the people. Zayd finally launched a rebellion and successfully liberated the city of Kufa till some of the people abandoned him for greed and gold offered by Ummayads. Zayd was eventually captured, mutilated and burnt.
Now, the people who followed Zayd began calling themselves Zaydis and didn't believe in the legitimate Imam Baqir. Although Zayd never called himself an Imam. Zaydis call him the 5th Imam so they're called Fiver Shias.
Now, every Muslim follows a religious Jurisprudence. There are 5 jurisprudence in Islam.
Jaffari (by Imam Jaffar 6th Shia Imam
Hanafi (by Abu Hanifa, a student of Jaffar who later founded Hanafi jurisprudence)
Maliki (by Malik ibn Anas)
Shafii (by Muhammad idris, a pupil of Malik)
Hanbali (by Iraqi scholar Ahmad ibn Hanbal)
So while the twelver Shias follow Jaffari Jurisprudence. Zaydi Shias follow Hanafi Jurisprudence found by a Sunni scholar Abu Hanifa.
Therefore, Zaydis are Shia by their political ideology but Sunnis by their religious Jurisprudence. It was also because Abu Hanifa was very supportive to Zaydis and made generous donations to their movements.
Hope it helps. Feel free to ask.