Dakini in this usage is someone who is using a supernatural or astral subtle body and who stays with the supernatural rulers, their associates and/or advanced yogis. These are females and they may or may not practice yoga but they are affiliated with yogis.

There are many other meanings for the word dakini. One can search at Wikipedia to get an overview.

An outpost in the astral planes, is a place which is established by an advanced yogi, where that person or someone assigned by him, resides. One can reach that place only if one has the vibration energy of the place, otherwise the place is invisible and cannot be reached.

Student yogis are sent, called, transferred or attracted to that place when a special technique is required which is not available elsewhere. Usually repeat visits are not allowed. One is given one transfer energy which is a one-time visit allowance. The reason for this is that the advanced yogi who is at that outpost has other assignments and must also complete his personal practice. He does not have the time to associate whimsically with others.