It's in vitro. So bit misleading can't know how it would be once it got into the body.
I will give a quick demo of how you can use pharmacokinetics to calculate the oral dose needed to get a clinical antiviral effect from the Lycoris radiata herb, based on the info from the in vitro study you quoted. We don't have all the data necessary to do the calculation, but we can use some guesses.
So the paper you quoted says the in vitro EC50 concentration of the most potent Lycoris radiata herbal extract used is 2.4 μg/ml (a concentration of 24 micrograms of the extract per ml).
The EC50 is a standard measure of antiviral efficacy. But to have useful clinical antiviral effects, you need to achieve blood concentrations that are at least 5 times the EC50 value. So we would want to achieve at least 5 x 2.4 = 12 μg/ml of the herbal extract in the blood.
Now the body has around 50 liters = 50,000 ml of fluids, so even if we had 100% bioavailability, you would need an oral dose of 12 x 50,000 = 600,000 μg = 600 mg of the extract, because whatever dose you ingest, it will be diluted in those 50 liters of body fluid (the blood and the fluids in and around the cells in the tissues).
Unfortunately, we don't know how much of the extract is present in the Lycoris radiata herb, but typically it might be say 33%, so now we need to multiply our 600 mg by 3 to get the actual dose of the herb required. So the oral dose of the herb required may be around 1800 mg = 1.8 grams.
But now we have to consider bioavailability, because for many herbs, the bioavailability can be low. We don't have any data for the actual bioavailability of the Lycoris radiata extract, but it could be anywhere in the range of 100% down to 1% or lower.
If it the bioavailability is low, say 1%, you now need an oral dose 100 times higher, which in this case would be an oral dose of 1800 grams = 1.8 kilograms!
The final pharmacokinetic factor you have to take into account is plasma protein binding: most substances (drugs or supplements) will bind to the proteins in the blood, and when they do this, they are lost (they no longer have an active effect in the body).
For many substances, the plasma protein binding can be high, like 90% or more of the substance binds to the proteins. So if the plasma protein binding of the Lycoris radiata extract were 90%, you would now have to multiply your oral dose by 10 to compensate, so that the oral dose now becomes 18 kilograms! Which is obviously far too high to be practicable.
Of course, we do not have the actual values for the bioavailability and protein binding of the Lycoris radiata extract, so in this case I have just entered pessimistic guesses. So this calculation of an oral dose of 18 kilograms is not accurate, but is given just to demonstrate how these calculations are done.
And this is what you usually get with many herbs: when you try to replicate the concentrations used in vitro, you find your required oral doses are in the kilogram range, which is just not viable.