Yes, Taiwan people are required to travel to Tibet with Tibet Travel Permits.
The scanned passport and the scanned Mainland Travel Permit for Taiwan Residents.
Tibet Travel Permits are only allowed to be applied in Lhasa. That is to say, only Lhasa travel agencies can apply the permits for you.
According to relative regulations, it is impossible to travel in Tibet without Tibet travel agency's organizations.
Some parts of Nyingchi Prefecture such as Yarlung Zangbo Grand Canyon, Nanyi Valley, and Ranwu part. Some parts of Ngari Prefecture such as Hoh Xil.
According to relative regulations, Tibet travel permit is free to apply, but the individual permits application service is not provided by TIbet travel agency. Foreign tourists have to follow the Tibet travel Agency which applies the permits for them.