Sastasha dungeon in main quest chain.

I've been in the duty finder for a while now trying to get into this dungeon to continue my story quest chain. I've tried to make a party for it but when I tried to go in got error that someone didn't meet duty requirements. I'm not sure having a required instance blocking main story progression is the smartest idea...

Or, you know, someone could have not met the requirements to enter, and this could not be a bug.

All your party must meet all requirements needed... that is, lv, job (if apliable) and having the dungeon unlocked... Otherwise you will have this error message.
The same applies to guildhest and forth :)