RuntimeError: Given groups=1, weight[512, 3, 1, 1, 1], so expected input[32, 1, 6, 4, 4] to have 3 channels, but got 1 channels instead

Described Error-

RuntimeError: Given groups=1, weight[512, 3, 1, 1, 1], so expected input[32, 1, 6, 4, 4] to have 3 channels, but got 1 channels instead

I am aware that this issue type has been raised several times, but none of them helped me solved my issue.
I am trying to Implement a FutureGAN model from here- GitHub - TUM-LMF/FutureGAN: Official PyTorch Implementation of FutureGAN

I followed all the steps mentioned in the Description and finally ran -

python /content/FutureGAN/train.py --data_root='/content/mmnist-2/train'

This yields an error -

 ... loading training configuration ... 
 ... saving training configuration to <_io.TextIOWrapper name='./logs/2021-08-24_172412/train_config.txt' mode='w' encoding='UTF-8'>
 ... creating initial models ... 
 ... initial models have been built successfully ... 
 ... saving initial model strutures to <_io.TextIOWrapper name='./logs/2021-08-24_172412/initial_model_structure_4x4.txt' mode='w' encoding='UTF-8'>
  0% 0/10140 [00:00<?, ?it/s]
Traceback (most recent call last):
  File "/content/FutureGAN/train.py", line 832, in <module>
    trainer.train()
  File "/content/FutureGAN/train.py", line 574, in train
    self.z_x_gen = self.G(self.z)
  File "/usr/local/envs/FutureGAN/lib/python3.6/site-packages/torch/nn/modules/module.py", line 357, in __call__
    result = self.forward(*input, **kwargs)
  File "/content/FutureGAN/model.py", line 307, in forward
    y = self.model(x)
  File "/usr/local/envs/FutureGAN/lib/python3.6/site-packages/torch/nn/modules/module.py", line 357, in __call__
    result = self.forward(*input, **kwargs)
  File "/usr/local/envs/FutureGAN/lib/python3.6/site-packages/torch/nn/modules/container.py", line 67, in forward
    input = module(input)
  File "/usr/local/envs/FutureGAN/lib/python3.6/site-packages/torch/nn/modules/module.py", line 357, in __call__
    result = self.forward(*input, **kwargs)
  File "/usr/local/envs/FutureGAN/lib/python3.6/site-packages/torch/nn/modules/container.py", line 67, in forward
    input = module(input)
  File "/usr/local/envs/FutureGAN/lib/python3.6/site-packages/torch/nn/modules/module.py", line 357, in __call__
    result = self.forward(*input, **kwargs)
  File "/content/FutureGAN/custom_layers.py", line 114, in forward
    x = self.conv(x.mul(self.scale))
  File "/usr/local/envs/FutureGAN/lib/python3.6/site-packages/torch/nn/modules/module.py", line 357, in __call__
    result = self.forward(*input, **kwargs)
  File "/usr/local/envs/FutureGAN/lib/python3.6/site-packages/torch/nn/modules/conv.py", line 388, in forward
    self.padding, self.dilation, self.groups)
  File "/usr/local/envs/FutureGAN/lib/python3.6/site-packages/torch/nn/functional.py", line 126, in conv3d
    return f(input, weight, bias)
RuntimeError: Given groups=1, weight[512, 3, 1, 1, 1], so expected input[32, 1, 6, 4, 4] to have 3 channels, but got 1 channels instead

I could resolve this issue by providing an input of just 1 channel,

python /content/FutureGAN/train.py --data_root='/content/mmnist-2/train' --nc 1

but that is not exactly how I wish to solve this. I would want my input to be in the RGB form.

Here are the details of my environment -
I am using a google colab notebook to do the training with all the steps here -
It is a regular Colab environment with Conda installed with all dependencies.

https://github.com/dhruvsheth-ai/FutureGAN/blob/master/FutureGAN-new.ipynb

Would appreciate any suggestions and if possible the change to be made in the code to solve this issue. Thanks!