Vyxal, 3 bytes

ẏEẇ

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Golf pilled sbcs maxxedmaxxer.

Explained

ẏEẇ­⁡​‎‎⁡⁠⁡‏‏​⁡⁠⁡‌⁢​‎‎⁡⁠⁢‏‏​⁡⁠⁡‌⁣​‎‎⁡⁠⁣‏‏​⁡⁠⁡‌­
ẏ    # ‎⁡Range [0, len input)
 E   # ‎⁢Each to the power of 2
  ẇ  # ‎⁣Partition the string into groups corresponding to each length
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Created with the help of Luminespire.