Example: "After decimal conversion it becomes [2, 7, 85, 2, 209, 1]"

Changing that section of the description would help a lot.

Recommend you assure the reader that the string will always be in chunks of 8, so that they don't need to make sure of index issues

278522091 in the description should be delimited. That would help tremendously.

Descriptions very unclear.

Please explain more how the results are derived ;-)

The description is not very clear.
Perhaps improve it, that it is clear, what to do!

Thanks!

removed. Thanks for your kata!

typo is fixed and random tests are added. remove the issue please.

Typo is fixed. remove the issue please.

return in sample code is written as "retrun".

Very very tiny issue, you wrote retrun instead of return in the c# code.

The bigger issue right now is your test cases. You need to have some random test cases for this kata, otherwise it would be super eeasy to cheat on it.

Fixed.

The Example Class doesn't have anything todo with the Tests. Since there are no example Tests you have no chance to know the class structure, without alot try and error.