I just tried to import the model locally, unfortunately it seems to contain an “If” operator.
The current version of Sentis does not support this operator. You can see a list of all of the operators we support and don’t support here:
https://docs.unity3d.com/Packages/com.unity.sentis@1.1/manual/supported-operators.html
I believe the other errors you are seeing are just following on from the model not being able to import. We will aim to make our debug errors clearer (issue 114 internally).