Since Chrome 71, SMB is now natively supported by Chrome OS and this Chrome extension/app is deprecated. The new implementation is an order magnitude or two faster and much more reliable.

On Chrome 71 or higher you can:

Open the files app

Click the “three dot menu” in the top right

Choose “Add New Service”

Choose “SMB file share”

https://chrome.google.com/webstore/detail/network-file-share-for-ch/ndjpildffkeodjdaeebdhnncfhopkajk