She's meditated before, the principle is familiar. Though irrelevant, of course.

As the man says, only the powder, and the voice.

"Walk forward, one step at a time. Begin to pour the powder, bit by bit, as you walk in a circle." 

She steps as instructed, allowing the powder to dribble out in front of her as she goes.

She pours, and pours, and halfway around, she knows she doesn't have enough to complete the circle.

"The powder will be enough," he insists, voice calm and gentle.

No space in her mind for doubts. Take the voice at its word.

Nope. She's still running out, did she think wishful thinking would be enough? 

"Stop. Open your eyes." 

She does so.

There's half a circle of powder on the floor.

"The next test is to see if a circle can contain you."

"How does that work?"

"Evidently, our magic sees you as a supernatural creature. Supernaturals keep magic within them, and can't achieve the right mindset for druidry. A werewolf who tries finds his temper flaring, a kitsune's fox spirit becomes restless. If you create a barrier of external magic, they cannot cross."

"I see."

She looks back at the half-circle and gathers the powder up into a neat little ball with a thought. She floats it over back into the jar.

"Now, I'll be pouring this in a circle around you. If the finished circle traps you, we should consider you essentially equivalent to local supernaturals. If not, we'll at least have another data point."

He starts to pour, walking a circle around her.

She waits patiently.

When the circle is finished:

"Try to step over it."

Foot?

That sure is a barrier in her way.

"Fascinating. You're interacting with the usual rules as if you're native to our world. Try moving something outside of the circle."

Hm. Inconvenient.

How about that jar? She wants it over there now.

The jar would never dare to question her judgment. It moves.

"Try bringing it into the circle. There are those whose powers extend beyond it, but can't operate on or within it."

Come over here, jar.

The jar comes most of the way there, and stops when it reaches the circle.

Then the circle should part so that the jar can get through.

In a word: no.