so i changed my code and i did something like this:
....
self.DropoutLayer = nn.Dropout(0.6)
self.FullyConnected = nn.Linear(8, 32*19*11)

the forward is:
def forward(self, inp):
        #print(inp.shape) #prints torch.Size([1, 8, 6, 128, 64])[batchsize, sequenceLength, channels, H, W]
        out = self.CNNLayer1(inp[0])
        out = self.CNNLayer2(out)
        out = self.CNNLayer3(out)
        out = self.DropoutLayer(out)
        print(out.shape)#torch.Size([8, 32, 19, 11])
        out = self.FullyConnected(out)
        return out

this error arises at the out = self.FullyConnected(out)
RuntimeError: size mismatch, m1: [4864 x 11], m2: [8 x 6688] at /pytorch/aten/src/THC/generic/THCTensorMathBlas.cu:266