"ModuleNotFoundError: No module named 'snappy'" error when running "warp to template" operation

I am using SNAP8.0 version, python3.8 version, this error occurs, do I need to install python3.6 to solve it?

I am going to use SEN-ET to calculate evapotranspiration, but I am stuck at this step, I hope it can solve the problem.

It could be that the reason for this error is Python 3.8. At least if you have not taken any action to make snappy work Python 3.8.
There is a guide on how to use sen-et. It might help you.
Technical Review of USER MANUAL FOR SEN_ALL_S2_S3_05032022_final.pdf

There is post which mentions the necessary steps to use snappy with Python 3.8.

Thank you very much for your reply
I have successfully run the “snappy” model after changing to Python version 3.4. But now I have a new problem, when I run the “SEN-ET” plugin, it shows that"Target product folder is not accessible or does not exist" and I don’t know what the reason is

That’s an error from SEN-ET, I can’t help with.
Does the folder exist? It might need to be created upfront.

Unfortunately, no contact point is provided on the project page: ESA Sen-ET (esa-sen4et.org)
You can directly send a mail to the prime contractor (gras@dhigroup.com)

Thank you very much for your answer.