I simply copied the code of latest inboxsdk.js file and replace the old one as mentioned in the google group post[Please see screenshot]. But, the SDK is not loaded and there is no error on the console as well. They haven't mentioned any extra steps for it except replacing the old code with a new one.

It seems I need to use webpack or parcel if I opt to use their npm package. But, we don't want to change our current build process just to support this inboxsdk library.

As it is still on Beta so they don't have a detailed documentation on how to use this latest version but you can read about the announcement and details from their google group, here is the link:

https://groups.google.com/g/inboxsdk/c/MAT_zImFu5I/m/N_7nDojRAgAJ