The TACAN station equipment on the ground has two parts, one provides bearing and the other one distance.
A VOR station on the ground only provides bearing.
There are also DME stations on the ground to provide distance.
A VOR onboard equipment can receive the distance signal from the TACAN "distance part" of the equipment on ground. And, of course, a VOR onboard equipment can receive also the distance signal from a DME station.
The C-101 CC doesn't have a TACAN equipment onboard, only a VOR.
Therefore, in the C-101CC, to get distance from a TACAN station, you need to tune the equivalent VOR frequency for that TACAN station channel.
In the C-101CC you can get the bearing from a VOR station of course, but not from a TACAN station.