1. Make sure your Google Drive Folder sharing settings is set to Public - see screen shot:
2. Copy the Google folder ID only from the URL website address bar - the ID is the part of the address highlighted in red
https://drive.google.com/drive/u/0/folders/1FjQDOifbswkb1R68bt5iyMklKAeaXlqa
3. Paste the ID into the box below
<iframe src="https://drive.google.com/embeddedfolderview?id= -----#grid" width="100%" height="500" frameborder="0"></iframe>